Every science was thus far advanced towards perfection, by the emulous diligence of contemporary students, and the gradual discoveries of one age improving on another. Sometimes unexpected flashes of instruction were struck out by the fortuitous collision of happy incidents, or an involuntary concurrence of ideas, in which the philosopher to whom they happened had no other merit than that of knowing their value, and transmitting, unclouded, to posterity, that light which had been kindled by causes out of his power. The happiness of these casual illuminations no man can promise to himself, because no endeavours can procure them; and therefore whatever be our abilities or application, we must submit to learn from others what perhaps would have lain hid for ever from human penetration, had not some remote inquiry brought it to view; as treasures are thrown up by the ploughman and the digger in the rude exercise of their common occupations. The man whose genius qualifies him for great undertakings, must at least be content to learn from books the present state of human knowledge; that he may not ascribe to himself the invention of arts generally known; weary his attention with experiments of which the event has been long registered; and waste, in attempts which have already succeeded or miscarried, that time which might have been spent with usefulness and honour upon new undertakings. But, though the study of books is necessary, it is not sufficient to constitute literary eminence. He that wishes to be counted among the benefactors of posterity, must add by his own toil to the acquisitions of his ancestors, and secure his memory from neglect by some valuable improvement. This can only be effected by looking out upon the wastes of the intellectual world, and extending the power of learning over regions yet undisciplined and barbarous; or by surveying more exactly our ancient dominions, and driving ignorance from the fortresses and retreats where she skulks undetected and undisturbed. Every science has its difficulties, which yet call for solution before we attempt new systems of knowledge; as every country has its forests and marshes, which it would be wise to cultivate and drain, before distant colonies are projected as a necessary discharge of the exuberance of inhabitants. No man ever yet became great by imitation. Whatever hopes for the veneration of mankind must have invention in the design or the execution; either the effect must itself be new, or the means by which it is produced. Either truths hitherto unknown must be discovered, or those which are already known enforced by stronger evidence, facilitated by clearer method, or elucidated by brighter illustrations.