The fifteenth century belongs to those rare epochs in the history of the world, in which all the efforts of the human mind are invested with a determinate and common character, and manifest an unswerving direction towards a single object. The unity of these endeavours, the success with which they were crowned, and the vigour and activity displayed by entire nations, give grandeur and enduring splendour to the age of Columbus, of Sebastian Cabot, and of Vasco de Gama. Intervening between two different stages of cultivation, the fifteenth century forms a transition epoch belonging at once to the middle ages and to the commencement of modern times. It is the epoch of the greatest discoveries in geographical space, comprising almost all degrees of latitude, and almost every gradation of elevation of the earth's surface. To the inhabitants of Europe it doubled the works of Creation, while at the same time it offered to the intellect new and powerful incitements to the improvement of the natural sciences in their physical and mathematical departments.

The world of objects, now as in Alexander's campaigns but with yet more preponderating power, presented to the combining mind the separate forms of sensible objects, and the concurrent action of animating powers or forces.