''SUCCESSFUL art can be depended upon to explain itself,'' wrote Clement Greenberg in Art and Culture. John Latham, a retrospective of whose work can currently be seen at the Museum of Modern Art in Oxford, doesn't agree. Latham, who is widely but not quite accurately regarded as one of the pioneers of Con-ceptual Art, has spent much of his long career trying to explain his own art. So much of it, in fact, that it is questionable which has more exercised him: the act of creation, or the act of exegesis. Within that small circle of people known as the British art world, Latham is famous for his explanations.
The catalogue to the present show includes, by way of an appendix, Latham's latest attempt to clarify what he refers to as his ''Time-Base Theory''. He clearly regards this as being of considerable import. It is said to contain the seeds of human salvation, so the fact that it is also said to be crucial to an appreciation of Latham's own work - the collages of burnt, dismembered or otherwise defaced books which he has been making since the 1950s - may prove incidental.
The world doesn't look like being saved for some while yet, however. ''Time-Base Theory'' is not very easy to follow. Take Latham on Man, for example: ''The human organism is considered as an Insistently Re-current Event (IRE) within a spectrum of IREs, and reproducing on the average about every 30 years. The 30 years is in band 25 and is written for purposes of visualising proportions as 10 to the power of 9 seconds within the range of A-U, 10 to the power of minus 23 seconds - 10 to the power of minus 21 seconds (roughly a thousand times the presently calculated age of the present...
