Subtitle ‘An Introduction to a Philosophy of Human Culture’ Yale University Press, 1944 by Ernst Cassirer.
Modern philosophy and modern science…had to prove that the new cosmology, far from enfeebling or obstructing the power of human reason, establishes and confirms this power. Such was the task of the combined efforts of the metaphysical systems of the sixteenth and seventeenth centuries. These systems go different ways, but they are all directed toward one and the same end. They strive, so to speak, to turn the apparent curse of the new cosmology into a blessing. Giordano Bruno was the first thinker to enter upon this path, which in a sense became the path of all modern metaphysics. What is characteristic of the philosophy of Giordano Bruno is that the term “infinity” changes its meaning. In Greek classical thought infinity is a negative concept. The infinite is the boundless or indeterminate. It has no limit and no form, and it is, therefore, inaccessible to human reason, which lives in the realm of form and can understand nothing but forms. In this sense the finite and infinite, περας and απειρον, are declared by Plato in the Philebus to be the two fundamental principles which are necessarily opposed to one another. In Bruno’s doctrine infinity no longer means a mere negation or limitation. On the contrary, it means the immeasurable and inexhaustible abundance of reality and the unrestricted power of the human intellect. It is in this sense that Bruno understands and interprets Copernican doctrine. This doctrine, according to Bruno, was the first and decisive step toward man’s self-liberation. Man no longer lives in the world as a prisoner enclosed within the narrow walls of a finite physical universe. He can traverse the air and break through all the imaginary boundaries of the celestial spheres which have been erected by a false metaphysics and cosmology. The infinite universe sets no limits to human reason; on the contrary, it is the great incentive of human reason. The human intellect becomes aware of its own infinity through measuring its powers by the infinite universe.
All this is expressed in the work of Bruno in a poetical, not in a scientific language. The new world of modern science, the mathematical theory of nature, was still unknown to Bruno. He could not, therefore, pursue his way to its logical conclusion. It took the combined efforts of all the metaphysicians and scientists of the seventeenth century to overcome the intellectual crisis brought about by the discovery of the Copernican system. Every great thinker–Galileo, Descartes, Leibniz, Spinoza–has his special share in the solution of this problem. Galileo asserts that in the field of mathematics man reaches the climax of all possible knowledge–a knowledge which is not inferior to that of the divine intellect. Of course the divine intellect knows and conceives an infinitely greater number of mathematical truths than we do, but with regard to objective certainty the few verities known by the human mind are known as perfectly by man as they are by God. Descartes begins his universal doubt which seems to enclose man within the limits of his own consciousness. There seems to be no way out of this magic circle–no approach to reality. But even here the idea of the infinite turns out to be the only instrument for the overthrow of universal doubt. By means of this concept alone we can demonstrate the reality of God and, in an indirect way, the reality of the material world. Leibniz combines this metaphysical proof with a new scientific proof. He discovers a new instrument of mathematical thought–the infinitesimal calculus. By the rules of this calculus the physical universe becomes intelligible; the laws of nature are seen to be nothing but special cases of the general laws of reason. It is Spinoza who ventures to make the last and decisive step in this mathematical theory of the world and of the human mind. Spinoza constructs a new ethics, a theory of the passions and affections, a mathematical theory of the moral world. By this theory alone, he is convinced, can we attain our end: the goal of a “philosophy of man,” of an anthropological philosophy, which is free from the errors and prejudices of a merely anthropocentric system. This is the topic, the general theme, which in its various forms permeates all the great metaphysical systems of the seventeenth century. it is the rationalistic solution of the problem of man. Mathematical reason is the key to a true understanding of the cosmic and the moral order. (pp. 15-16, An Essay on Man, 1944)
Such is the strange situation in which modern philosophy finds itself. No former age was ever in such a favourable position with regard to the sources of our knowledge of human nature. Psychology, ethnology, anthropology, and history have amassed an astoundingly rich and constantly increasing body of facts. Our technical instruments for observation and experimentation have been immensely improved, and our analyses have become sharper and more penetrating. We appear, nevertheless, not yet to have found a method for the mastery and organization of this material. When compared with our abundance the past may seem very poor. But our wealth of facts is not necessarily a wealth of thoughts. Unless we succeed in finding a clue of Ariadne to lead us out of the labyrinth, we can have no real insight into the general character of human culture; we shall remain lost in a mass of disconnected and disintegrated data which seem to lack all conceptual unity. (p. 22)