At times, conceptual art is unduly discredited, which is probably due to that nasty "c" word that poets sometimes shy from these days. What often attracts me to such work is the real physical or material construction. Spaciality and temporality are both at issue. Among the several artists interviewed in this book, Barry, Morris, and Smithson stand out as particular geniuses. Throughout, the interviewer Patricia Norvell is as sharp as a tack. Here's a bit from the Robert Barry interview, 1969:

PN: What about the question of judgment, whether a piece is good or bad?
RB: It becomes very difficult. I don't even think that there'll be that judgment. I think that the whole definition of art will be changing. The thing just is. I mean, how can you criticize a carrier wave? How do you criticize inert gas?
PN: In cases like that I would think you would have to focus on the idea of what was being done.
RB: Right. Either you accept it as a worthwhile idea or not. But you can't say that this line is too long, or this line is not long enough, or these colors don't work together, or they're very harsh, you know. I mean, there'll just have to be some other way of dealing with it, which I think is good.