There have been spectacular conversions from a debonair tolerance of collecting to fierce opposition. The Cycladic Spirit,'' a book about the finest private collection of Cycladic art in existence, published by Harry N. Abrams, is now campaigning hard for the adoption of Unidroit in Britain. This provoked an enraged Eisenberg to reply with a blistering, ''Enough is enough, Lord Renfrew,'' in the September-October issue of Minerva. But Eisenberg himself is clearly distressed by the havoc. The dealer has told me that he never buys fragments from monuments, nor will he do business with runners who come straight from the source countries.
Some partial solutions are conceivable.