The System of Nature, Volume 2

If man possessed the courage, if he had the requisite industry to recur to the source of those opinions which are most deeply engraven on his brain; if he rendered to himself a faithful account of the reasons which make him hold these opinions as sacred; if he coolly examined the basis of his hopes, the foundation of his fears, he would find that it very frequently happens, those objects, or those ideas which move him most powerfully, either have no real existence, or are words devoid of meaning, which terror has conjured up to explain some sudden disaster; that they are often phantoms engendered by a disordered imagination, modified by ignorance; the effect of an ardent mind distracted by contending passions, which prevent him from either reasoning justly, or consulting experience in his judgment.