Kant claims that natural sciences require a “pure part” ,(reiner Teil), which has to be formulated a priori by philisophy. This pure part, is enunciated by Kant in his Metaphysische Anfangsgründen der Naturwissenschaften in relation to Netwon’s Pincipia, whose steps is closely follows. This Kantian Work also represents an instance of classical “foundation” by philosophy in the particular sciences.In this paper the particularities of Kant’s foundation in Newton’s physics come under close scrutiny, and his huge speculative effort on this issue (...) is shown to be equivocant in content, inconsistent in form and probably useless. (shrink)