In this essay the author examines the affirmation of the concept of mathe-matical relations in modern philosophy and its applicability to the disci-plines of physics and mathematics and to psychology. The first part high-lights the prominence given to the concept of mathematical relations in Hobbes’, Locke’s, Leibnitz’, and Hume’s gnosiologies. The second part documents how modern mathematics has gone on to mathemetize the con-cept. In the third part, Wolff’s role is closely examined to illustrate the relevance of relations to philosophy in general. The author also discusses Kant’s use of relations to describe the perception of phenomena and to dis-cuss the representability, in mathematical terms, of the activity of con-sciousness.