Jarrett Earnest at Artforum:
It takes a particularly agile intelligence to continue coming to terms with several generations of new art, as regularly, and for as long, as Peter did. Things change and so must arguments, though without losing credibility. One way Peter maintained that trust was by narrating his own inner process, attending to ambivalence and contradiction in print. Changing your mind was not a failure, but a freedom to be carefully guarded. Once, he described this to me as his willingness to entertain the thought that anything, no matter how sacred or unimpeachable, might just be bullshit after all. Then what? Could you trace it backward back into meaning? In conversation Peter often evoked the fourteenth-century spiritual tract The Cloud of Unknowing, which teaches a method of contemplation for willfully releasing all prior conceptions of life on this earth and pushing into this great “unknowing” where God finds you. Acclimate to being uncomfortable and just stay there until the miraculous appears. It lent a theological framework to the techniques he’d developed for encountering art.