In this survey of the preconceptions of the early Greek philosophers I have employed the terms of the judgment without apology. The justification for this course must come ultimately, as for any assumption, from the success of its application to the facts. But if "logic" merely formulates in a schematic way that which in life is the manipulation of concrete experience, with a view to attaining practical ends, then its forms must apply here as well as anywhere. Logical terminology may therefore be assumed to be welcome to this field where judgments are formed, induction is made from certain facts to defined conceptions, and deductions are derived from principles or premises assumed. Speaking then in these terms we may say that the Pre-Socratics had three logical problems set for them: First, there was a demand for a predicate, or, in other words, for a theory of the world. Secondly, there was the need of ascertaining just what should be regarded as the subject, or, otherwise stated, just what it was that required explanation. Thirdly, there arose the necessity of discovering ways and means by which the theory could be predicated of the world and by which, in turn, the hypothesis erected could be made to account for the concrete experience of life: in terms of logic this problem is that of maintaining an efficient copula. It is not assumed that the sequence thus stated was historically observed without crossing and overlapping; but a survey of the history of the period will show that, in a general way, the logical requirements asserted themselves in this order.