This impressive production feels like more than one book. It is not just that it consists of two oddly-matched parts, a series of essays about archi tectural language followed by 18 pieces on particular terms. The feeling that it is more than one thing really takes hold in the second part, arranged alphabetically, starting with 11 pages on 'Character' and ending with three on 'User'. In between come particularly hefty treatments of 'Form', 'Function', 'History', 'Memory', 'Nature', 'Space' and 'Truth'.
These are self-contained arguments running to between 15 and 25 double-column pages, in which Forty defines architectural Modernism as a system of thought by looking at the ways in which it has been talked about. The same figures recur - Soane, Semper, Ruskin, Rossi, Tschumi and Bill Hillier turn up with surprising regularity. But although the book possesses that kind of consistency, it does not really repeat itself or make you feel this or that part of the discussion could well come under another heading.
Perhaps not many people will read the book in alphabetical order as I did; surely the book was not written in the order it is printed. But still one wonders and secretly wishes it were so; there is no ending, yet technically the last words (in 'User') are 'the welfare state', which bears on a submerged social theme that becomes more evident in the later stages. It is hard to talk about a book without the idea of later stages, but does this book really have stages? Yes and no.
Its form is tantalizingly perplexed: the same ground is covered in many of the separate entries, but not quite the same, for one's progress is also like fitting together the pieces of a jigsaw; thus the feints and dodges of successive terms bear a family resemblance to each other, and one gets better at playing the game the book has set up.
The game is that of unmasking deception and straightening out confusion. Entries do not follow a rigid formula, but they often begin by setting a temporal frame - the term in question had a brief fashion in the 1960s, or had been around for centuries but used in a distinct series of ways until convulsively redefined around 1970 - followed by distinguishing several main uses which are then each traced historically. Sometimes that means going back to Plato, sometimes to the Renaissance, sometimes only as far as Durand or Kant.
Occasionally, with terms like 'Flexibility', 'Transparency' or 'User', there is no very distant lineage to trace, so these can be brisker, more pungent entries, where the author whizzes through sizeable mental tracts without stopping anywhere long or quoting from anyone.
While Forty's quotations are apt, and some of the more important positions do need to be seen in the round, quotations interrupt the flow of his synthesising thought, which is what I most enjoy in the book. He is a masterful summariser of complex intellectual developments. Particularly good in this way are the pages, not all in one place, on the relation of Aldo Rossi (as author not architect) to the rest of post-war Italian culture, or the whole entry on 'Order', especially the treatment of disorder in cities.
About words and their meanings Forty is sceptical; he sees them as basically treacherous, spreading confusion, blurring categories, erecting phantasms into solid existence. He calls for the dissolution of the most important Modernist terms, 'Form' and 'Function' in particular having outlived their usefulness. But about texts he is less sceptical, and so the essays on problematic terms follow them along trails made up of key texts.
Forty believes more than I do that what appears in books has its sources in earlier books. The version of Ruskin purveyed here is a case in point: he is hardly ever mentioned without reminding us of the dependence of his views on German Romantic thought; I am not equipped to contest this except to question the emphasis. Other influences, perhaps stronger, don't come into it because they are not so easily incorporated in the story Forty is telling. Perhaps the better you know a writer, the less you enjoy seeing him or her pressed into one of these chains of intellectual inheritance.
Near the beginning, Forty admits to two sources of inspiration himself, one unexpected, the other less so: Roland Barthes' The Fashion System and Raymond Williams' Keywords.
These two writers are so diverse, and their relation to architecture so hard to trace, that they cause one to reflect on what a strange and original artefact this book is. I confess I do not find its categorising method congenial.
All the more reason to attest that it is a forceful, clear and sophisticated exposition of the role of conceptual thought in architectural discourse, and that it will have something to teach anyone who has ever investigated the subject.
Robert Harbison is professor at the University of North London