Page:An Essay on the Principle of Population (1798).djvu/406

 The obscurity that involves all metaphysical subjects, appears to me, in the same manner peculiarly calculated, to add to that class of excitements which arise from the thirst of knowledge. It is probable that man, while on earth, will never be able to attain complete satisfaction on these subjects; but this is by no means a reason that he should not engage in them. The darkness that surrounds these interesting topics of human curiosity, may be intended to furnish endless motives to intellectual activity and exertion. The constant effort to dispel this darkness, even if it fail of success, invigorates and improves the thinking faculty. If the subjects of human inquiry were once exhausted, mind would probably stagnate; but the infinitely diversified forms and operations of nature, together with the endless food for speculation which metaphysical