This title was first published in 2002: This text considers the applicability of mathematics to the study of natural phenomena. The possibility of such an application is one of the fundamental assumptions underlying the enormous theoretical and practical success of modern science. Addressing problems of matter, substance, infinity, number, structure of cognitive faculties, imagination, and of construction and mathematical object, the author examines mathematical (geometrical) objects in their relation to geometrical or intelligible matter and to imagination. Exploring questions in the history of philosophy and science of late antiquity and early modernity, the key thinkers of focus are Plotinus and Descartes (with the occasional appearance of Plato, Aristotle, Euclid, Proclus, Newton and others), in whom the fundamental presuppositions of ripe antiquity and of early modernity find their definite expression.