It is interesting that Richard Serra, who is not short of offers of highly promising locations for which to make site-specific sculptures, accepted the Tate’s invitation to do something in their domineering central hall – a space ostensibly built for showing sculpture but serving that purpose rather badly, partly because it makes the things put into it look as if they were lost at the bottom of a well, partly because its huge Ionic columns dwarf other forms in the same field of vision. For that matter, it is interesting that Nicholas Serota has ignored the space’s bad reputation in restoring it to its original purpose and shape, this at some expense because of the need to strip away various accretions which had been added out of despair at the difficulty of showing sculpture there, as against certain kinds of painting – Picasso’s Meninas series, for example – that have looked quite good on the walls.

Its flaws as a setting for sculpture are the consequences of a single-minded pursuit by its main architect, John Russell Pope, of its underlying purpose, which was to provide a famous dealer in need of respectability, Lord Duveen, with a chance to display his munificence on a colossal scale. So the space seems designed to diminish any person or thing that enters it. Completed in 1937, it also has something of the bullying pomposity characteristic of official buildings erected in countries under totalitarian rule. Meanwhile at the British Museum Duveen was employing Pope to execute a takeover of our greatest artistic possession, or ward, the Parthenon Marbles. Before they could be installed in the house he had built for them the Luftwaffe mercifully destroyed it. Blindly the British Museum Trustees rebuilt it and in 1962 moved the sculptures in. Till then they had, of course, been one of the seven wonders of the world. Since then any pleasure still to be had from looking at them has been mixed with a good deal of pain.

There has been no blindness, though there has been risk, in Serota’s decision to put sculpture and only sculpture in Pope’s tripartite hall at the Tate, the South Duveen Gallery, the Octagon and the North Duveen Gallery. He has managed to choose and place and light various combinations of pieces from the permanent collection – and related borrowed items – in viable ways, works by Rodin and by Epstein especially. And he has initiated a highly interesting series of exhibitions ‘which demonstrate a sculptor’s response to the space’. Serra is the third sculptor invited to respond: his answer, Weight and Measure, will remain there until 15 January and will then be dismantled, doubtless for good.

The initial guest, Richard Long, followed his usual bent by focusing attention on the floor and so by-passed the problem normally posed by these galleries – that the space up above crushes sculptures and visitors alike. The three volumes were turned into three areas, thanks to the visual magnetism of three compositions which were not only beautiful in themselves and cleverly contrasted but related nicely to the shapes of their respective areas. The work was a triumph, but one achieved by slipping through Duveen’s gargantuan legs rather than by standing up to him. The next guest, Anthony Caro, took Duveen on. But Caro is an artist whose rich creativeness is not matched by his critical intelligence, and this has never been more evident than it was in his contest with Duveen. He appears in his naivety to have made two strategic errors: to be too easy-going; to be too greedy. He seems to have supposed that he could dump a selection of existing works in this rebarbative space and move them around till they looked all right; and he seems to have supposed that the way to handle an enormous space was simply to fill it up, possess it, stuff it. The consequence was that the sculptures got in one another’s way in the field of vision, so that a piece more than ten feet high and seventy-five feet long became invisible. Caro’s folly betrayed his own art and betrayed the Tate’s act of faith that the space could be redeemed.

Serra typically took the problem seriously. How he did so is well documented, first in an interview with him recorded on 27 May and published in the exhibition catalogue, secondly in a lecture given at the Tate on 1 October and published in the current issue of the Art Newspaper. I quote from the interview:

The architecture as a whole is overblown, authoritarian and a bit heavy-handed. It is a little bit ‘Thou shalt walk this way and then take the side aisles.’ What I wanted to do, and what I hope I am doing, is to bring another relevance to that space ... I want to expose it by placing two volumes in the Duveen Galleries, leaving the octagon empty ... The forged blocks will be centred on line with the main axis, placed 130-140 feet apart. They are approximately nine feet (exact measure 108½ in) wide, scaled to the distance between the central columns in the Sackler Octagon. One element is 68 inches high, the other is 60 inches high. The lower element is placed in the south gallery, the higher element in the north gallery, so that when you enter the hall, they will appear level due to perspective. Both elements will be 41 inches thick. I wanted a physical scale and mass which would act as counterweight to the columns and the weight of the stone ...

   I started out considering five elements. We stood people at various locations over the distance to establish a scale reference ...

   I did not reach a conclusion until after I had reduced the elements to four and three and at three I still had one in the centre. At that point it became clear to us that we had to remove the work from the centre and see if we could hold the space with two elements. Only then did we feel that we were moving in the right direction. (I say we because Clara [Weyergraf-Serra] is part of the dialogue, always and continuously) ...

   I started with circles. 1 started with the ideas of using forged rounds, taking the scale of the rounds from the scale of the columns. I dropped the idea. Conceptually it falls right into the post-modernist trap of contextualisation ...

   I had recently installed a large forged octagon in front of a Romanesque church in Burgundy. To work with octagons was on my mind. And for a while I thought I would use them, but the active shape of the octagon draws too much attention to itself. It is too busy for this space. It can be too easily read as an interesting object ...

   I dismissed the idea of using cubes as quickly as I dismissed the idea of using octagons and for the same reason. They would have been read as objects in the galleries. I’ve only forged one large cube. It is very absolute to forge a cube ...

   We dropped the idea of using five parts because the seriality of their placement would have imposed a formal composition on the hall, isolating the installation from the conditions of the place. We only concluded the final number of elements after we started to work with full-scale models ...

The solid steel blocks have not come from the forge as regular, perfectly geometric cuboids. As the surfaces differ from those of minimal sculpture in being, through the workings of industrial processes, variegated and random, the forms are palpably imperfect: the top plane of the nearer cuboid has a definite slope; everywhere edges that look as if they might have been sharp and hard – as they are when Serra is working, as he mostly has, with steel plates – are here blunt and soft. Though these irregularities have again come about in the course of the manufacturing process, not through gestures of the artist’s hand, the effect is analogous to that of Mondrian’s brushmarks, palpable brushmarks which break up surfaces that would otherwise have been immaculate and predictable, giving them relief and animation. As those brushstrokes are an echo of the free painterly handling in Mondrian’s early romantic landscapes, the roughness of Serra’s blocks relates to his early sculptures made by splashing molten lead onto a wall and floor. Obviously, Serra’s untidiness is still more akin to the cultivated imperfections in Newman’s straight lines.

Perhaps the first impression on coming into the south gallery is one of surprise at the daring of the work’s absolute austerity. Perhaps the next, on approaching the first block, is that there’s a deep solemnity about it which counters any feeling of surprise by conferring a sense of inevitability on the work. At the same time, the initial illusion that the blocks are the same height, followed by doubts on getting nearer as to whether this is so, engage the mind in the question of height, so that, when you get to the first block, you find – if you’re between, say, five foot five and six foot tall – that its height is a tease. You can more or less see over it – certainly you can see the top plane, especially as the slope rises away from you – but you are still slightly bemused as to how its height relates to your own: it’s a bit like dancing with an unfamiliar partner who isn’t ridiculously taller or shorter than yourself. (I imagine that lofties and titches cannot respond to this work as others do: this applies to a lot of minimal art, the impact of which is so often bound up with its height in relation to ours.) As you leave that block behind and approach the other, there is a point at which you realise that this one is going to be higher. When you reach it you find – unless you are inordinately tall – that its top is above the level of your line of sight. Nothing teasing here; it is so decidedly something high that it might as well be as high as a house. This makes it more menacing than the first block. So does the fact that its edges look relatively sharp where those of the other are softened for the eye (as my colleague Marla Prather pointed out) by the way light falls on that visible top plane.

Everything about Weight and Measure – how the blocks relate to each other, how they relate to the space, how they relate to yourself – is a function of that difference between a barrier that is like a garden fence across which you can chat with a neighbour and a barrier that might as well be Gordale Scar. The blocks are utterly different entities though they are identical in their dimensions but for a difference of 13 per cent in their height. I am reminded of something said to me by Giacometti about the way in which the crucial differences in how art operates are physically very small: ‘It’s always extremely limited. Like the fact that you can only survive with a temperature of – what – between 36 and 39 degrees – and that’s already very very bad. So you can only really live with a temperature between 36.8 and 37.8. And everything’s like that.’

Contemplation of the blocks triggers a variety of visceral responses. Their massive sense of solidity weighs me down, making me feel that my own body is very firmly planted on the ground. The energy emanating from them transfers itself to my body, so that it feels lifted by that energy. The taller block gives off an energy which has more intensity and speed than the other’s: as I stand looking at it from its far side, my body is assailed not only by the force emanating directly from it but by waves of force which seem to have bounced back from the surrounding walls so that they bombard me, like hailstones, from all sides and above. Turning away from the block and looking towards the end of the gallery, I’m amazed to find that that academic, bombastic architecture suddenly looks beautiful: the sculpture has diminished its theatricality, and in looking more sober it also looks finely proportioned. Turning around and walking back to the smaller block, I invariably find on getting there that it’s a soothing, calming presence. It is (as Serota said to me) like coming home. It seems to be hospitable, like a tomb in which I can imagine myself at rest. The measurements which in reality would be relevant in a practical sense to its becoming that are no different from what they are in the other block, which – here again, the relative height is everything – seemed forbiddingly impenetrable.

The relationship between the two blocks is not experienced as a relationship between two objects set up in a space. It does not present an interaction between forms perceived together from various points in that space, as did, for example, that marvellous installation which Serra created two years ago at the Kunsthaus in Zurich, The Hours of the Day. The forms in that space were like actors seen in their places on a stage; the forms in the Tate are like shots of single actors alternating to build up a scene in a film. The relationship is one that is constructed in the spectator’s mind through successive – and interacting – experience of the separate blocks. This is why I think Serra was right in principle when he answered a question after his lecture with the assertion that it didn’t matter if people were drifting around and getting in the way. But in practice it is true, I’m afraid, that the work looks at its most impressive when there are no people around. Their absence is especially helpful in regard to the crucial experience of walking from one block to the other. The space between the blocks is not a space contemplated but a space traversed. Every step taken in walking from the first to the second across the empty floor of the octagon seems momentous: how much distance has still to be covered seems a matter of great significance, because of the gradual heightening of tension and expectation. Hence the crucial importance of Serra’s realisation that he had to have two units, not three: there had to be room left for a sizeable area of emptiness.

Walking from the second block back to the first is more an experience in visual ambiguity, as the sense changes with every step as to how the height of the one now ahead relates to that of the one now behind. Here again the work has to do with generating a succession of experiences unfolding in time. In the interview, Serra came to talk at length about Barnett Newman and one of his themes was this: ‘In Newman’s paintings space and mass which are formed between the vertical divisions are experienced as you walk or scan the field. It is an experience that unfolds in time ... When you reflect upon a Newman, you recall you experience, you don’t recall the picture.’ All the same, there are aspects of Weight and Measure which are less relevant to Newman than to Rothko. Given that there are two complementary modes in our relationship to works of art, the sense of envelopment and the sense of confrontation, Newman’s paintings tend to induce the latter sensation to such a degree as virtually or entirely to exclude its counterpart, whereas Rothko’s paintings tend to induce the two sensations alternately. And I think that Weight and Measure functions in these terms – I haven’t yet worked out how – in ways analogous to the Tate’s series of Rothkos in 1958-9.

Weight and Measure confirms with exceptional power certain familiar laws pertaining to the functioning of the energy which seems to be contained in great sculpture. First, that the energy emanating from certain forms, while not measurable by any instrument, has effects on an observer’s nervous system which appear as real to that observer as physical pain or pleasure. Second, that this energy functions in a way analogous to light, seeming to fill a space as light objectively bathes it. Third, that a form too many in a space can interfere with the waves of energy so as to prevent them from totally filling the space. Fourth, that when the waves of energy completely fill a space, that space, in becoming altogether vibrant, becomes altogether beautiful, regardless of its proportions and of the quality of its architectural detail.

Weight and Measure consists of two elementary forms made on an unassuming scale, the scale of human beings, set up in a space designed to make man feel small. It masters that vast space, matching inordinate size with the force of its energy. None of the precepts that has guided the Modern movement has had more resonance than ‘Less is more.’ Weight and Measure has turned out to be one of the supreme manifestations of that principle, a milestone in the art of this century. It’s true that ‘less is more’ can apply to time as well as space, but it’s sad that Weight and Measure will stay – which means, being site-specific, exist – for so short a time. Ironically, it has the look of a great ‘timeless’ monument.