The square which is presented to me obliquely remains a square, not because this apparent diamond shape brings to mind the familiar form of the square seen directly in front of me, but because the diamond shaped appearance in an oblique presentation is immediately identical to the square appearance in a frontal presentation, because, along with each of these configurations, I am given that orientation of the object which makes it possible, and because these shapes are presented in a context of relations which, a priori, equate the various perspective presentations with each other.