The overthrow of the Grecian empire and the discovery of the new world, suddenly and at once introduced into Western Europe vast and varied treasures of historical, physical, and philosophical knowledge. In this brilliant epoch of the fifteenth century, a new world of thought was, as it were, laid open. A new era of science would have been founded, and a veritable reformation of the whole Christian life must have ensued, had not the moral corruption and the political disorders of the period been gross beyond description. But for all this, how much is there to admire in the Platonic writers of the fifteenth century, among whom Germany, after Italy, produced the most famous and the greatest number? When we take up, even now, any one of their works, and contemplate therein their comprehensive liberal pursuit of science, their mild, antique spirit, their noble form, and their quick recognition of the beautiful, we can not turn from them without regret to that new state of barbarism into which, during the sixteenth and part also of the seventeenth century, science was plunged by the rampant spirit of party and controversy.
At last, however, peace and quiet returned again to Christian lands and states, and slowly, and by degrees, to the minds also of men. And now was it, in the eighteenth century, and especially toward the middle of it, that out of this apparent and superficial peace, a new science, or a new light, or at least a new diffusion of it, seemed ready to arise. Simply regarded in a scientific point of view, this philosophical endeavor of the eighteenth century, and the most memorable of the systems to which it gave rise, occupied our attention in the very opening of these Lectures. Here the immediate object of our consideration is not this new science itself, whether true or false, but rather the influence on the age, and on life in general, of this modern mode of thinking, as generally diffused and prevalent.
Much, undoubtedly, has been discovered or newly learned in the natural sciences and in the domain of history; many too have been the bold ventures, at least, and novel essays in philosophy. This new wisdom, moreover, was taught and disseminated far more universally than ever before had been the case; while even the agreeable feeling produced by the moderation of the intellectual spirit now prevalent, greatly promoted its wide and rapid diffusion. But at a later period this enlightenment, so rapidly and so widely diffused, which, moreover, was taken only in a negative sense, was soon recognized to be unsatisfactory and superficial, while also the theory of popular liberty and independence which was grafted thereon, and claimed, or at least wished to be rational, bore the bitterest and worst of fruits.