Britain's John Berger has got to be the widest-ranging Marxist art critic around; and in these 23 assorted essays, 1966-79, he almost apotheosizes into a butterfly. He'll poke around at anything anywhere that might ratify his rather wistful dream of truly socio-historical art. "Why We Look at Animals," the longish lead piece, throws together every quote Berger seems to have been able to find in order to build a finally less-than-stirring argument: that the modern zoo is the culmination of the "marginalization" capitalism imposes even on beasts. His trendy essays on photography, which comprise the second section, try to out-Sontag Sontag (whose thoughts he credits with prompting some of his); but they are thin, wishy, or even obviously silly. (An August Sander photo of suited peasants on their way to a dance supposedly illustrates the succumbing of a perfectly good working-class sartorial fashion to the "class hegemony" of suits). The third section focuses variously on painting and painters. And here Berger writes that primitives, Grandma Moses included, do not "emigrate" to the standards of the ruling class as "professionals" do because their "whole experience is one of being excluded from the exercise of power. . . ." But he also maintains that Ralph Fasanella, the New York naive painter, denies perspective as a protest against the city's dehumanization (Berger is all over the place in this one). Yet on other topics--the Dutch de Stiff group, Turner, Courbet ("lawless visibility"--brilliant phrase)--Berger is adventurous and expanding. A messier, more Procrustean critic would be hard to find, farfetched as often as he is just; yet Berger always holds your interest--which, considering the present state of art criticism, is no mean accomplishment.