With Diogenes and Democritus, who were little if at all older than Socrates, the Presocratic period is legitimately held to end. During the second half of the fifth century B.C., particularly during the Peloponnesian War and under the influence of the mature Socrates and the Sophists, the old cosmological approach--by which the primary aim was to explain the outside world as a whole, man being considered only incidentally--was gradually replaced by a humanistic approach to philosophy, by which the study of man became no longer subsidiary but the starting-point of all enquiry. This reorientation was a natural development; in part it was determined by social factors, but in part, as will have become apparent, it was the product of tendencies in the Presocratic movement itself.