In the _Introduction_ to the _Prolegomena_ there is no such confusion of the two problems, but matters are made even worse by the omission of all reference to Hume’s analysis of the causal axiom. Only Hume’s treatment of the concept of causality is dwelt upon. This is the more unfortunate, and has proved the more misleading, in that it is here that Kant makes his most explicit acknowledgment of his indebtedness to Hume. In §§ 27 ff. of the _Prolegomena_ both problems reappear, but are again confounded. The section is preceded by sentences in which the problem of experience is emphasised; and in keeping with these prefatory remarks, Kant represents “Hume’s _crux metaphysicorum_” as concerning only the concept of causality (viewed as a synthetic, and professedly _a priori_, connection between concrete existences). Yet in § 30 the causal axiom is also referred to, and together they are taken as constituting “Hume’s problem.” Now if we bear in mind that Hume awakened Kant to both problems--how _a priori_ knowledge is possible, and how experience is possible--this confusion can easily be understood. Kant had already in the early ‘sixties studied Hume with profound admiration and respect.[259] In the period subsequent to 1772 this admiration had only deepened; and constantly, as we may believe, Kant had returned with fresh relish to Hume’s masterly analyses of causality and of inductive inference. It is not, therefore, surprising that as the years passed, and as the other elements in Hume’s teaching revealed to him, through the inner growth of his own views, their full worth and significance, he should allow the contribution that had more specifically awakened him to fall into the background, and should, in vague fashion, ascribe to Hume’s teaching as a whole the specific influence which was really due to one particular part. By 1783, the date of the _Prolegomena_, Kant’s first enthusiasm over the discovery of the fundamental problem of _a priori_ synthesis had somewhat abated, and the problem of experience had more or less taken its place. This would seem to be the reason why in the _Prolegomena_ he thus deals with both aspects of Hume’s problem, and why in so doing he gives a subordinate place to Hume’s treatment of the causal axiom. But though the misunderstanding may be thus accounted for, it must none the less be deplored. For the reader is seriously misled, and much that is central to the Critical philosophy is rendered obscure. The influence which Kant in the _Prolegomena_ thus ascribes to Hume was not that which really awakened him from his dogmatic slumber, but is in part that which he had assimilated at least as early as 1763, and in part that which acted upon him with renewed force when he was struggling (probably between 1778 and 1780) with the problems involved in the deduction of the categories. It was Hume’s treatment of the causal axiom, and that alone, which, at some time subsequent to February 1772,