IT is a scandal to philosophical scholarship, and not least to German philosophical scholarship, that, more than a hundred and fifty years after the publication of the Kritik of Pure Reason, we still lack a commentary comparable with such works as that of Pacius on the Organon of Aristotle or even that of Adam on the Republic of Plato. Of all the authors who write about Kant’s greatest work there is none who condescends to explain it sentence by sentence: Hans Vaihinger, who alone set out to do so, attempted to write a commentary, not only upon the Kritik, but upon all its previous commentators; and, as was but natural, he gave up this impossible task when he had proceeded but a little way. In the absence of a detailed commentary we have an inevitable welter of conflicting opinions about Kant’s doctrines. More serious still, the unfortunate student and even, if I may judge from my own experience, many teachers of philosophy have the vaguest idea as to the meaning of Kant’s words. There are sentences in which the reader is unable to decide to which of several nouns the relative and demonstrative pronouns refer, or which of two nouns is to be regarded as subject and which as object. In vain do we look for a reliable guide even in these elementary matters; and the plain fact is that most students find many passages, and too often crucial passages, to which they can attach no meaning at all. It is not surprising that they accept the opinions of others at second-hand without being able either to confirm or to criticise them.