The texture of the human mind is so delicately fine, that it is often affected by causes which to the judgment are imperceptible; and, although Bruce does not declare it, yet it is not improbable that his melancholy sprang mainly from the thought, how little, after all, his discovery was worth the trouble it had cost him. It had, it was true, "baffled the genius, industry, and inquiry of both ancients and moderns for near three thousand years," and it was equally true that "a mere private Briton had triumphed over kings and their armies;" but, after all, did the source of the Nile, in the great scheme of creation, rank as an object worthy of so much attention? What proportion did a puny rill, that might flow through a pipe of two inches in diameter, bear to that vast rolling mass of waters which gave fertility to Egypt? And again, Was the "hillock of green sod before him" actually the source of that immense river, or did it only nourish one of the innumerable streams which fed the "father of waters?" In short, had not human curiosity been pushed too far, and had it made any other discovery than of its own weakness? Bruce, drooping, bending in despondency over the fountains of the Nile, forms a striking picture, strongly exemplifying the practical difference between moral and religious exertions; for although, among men, he had gained his prize, it may justly be asked, What was it worth? The course of a river is like the history of a man's life, and all of it that is useful is worth knowing; but the source of the one is as the birth of the other, and "the hillock of green sod" is the "infant mewling and puking in its nurse's arms."