6. The progress of Moral Science is the more and more perfect development of the Natural Law in the heart of man, a psychological, not an ontological development. And Moral Science does progress. No man can be a diligent student of morality for years, without coming to the understanding of many things, for which one would look in vain in Aristotle's _Ethics_ and _Politics_, or in Cicero, _De Officiis_, or even in the _Summa_ of St. Thomas, or perhaps in any book ever written. New moral questions come for discussion as civilization advances. The commercial system of modern times would furnish a theme for another De Lugo. And still on this path of ethical discovery, to quote the text that Bacon loved, "Many shall pass over, and knowledge shall be multiplied." (Daniel xii. 4.) _Readings_.--St. Thos., Supplement, q. 65, art. 1, in corp.; _ib_., q. 65, art. 2, in corp., and ad 1; Hughes, _Supernatural Morals_, pp. 67, 68, reviewed in _The Month_ for August, 1891, pp. 542, 543. SECTION IV.--_Of Probabilism_. 1. Sometimes conscience returns a clear, positive answer as to the morality of an act contemplated. True or false the answer may be, but the ring of it has no uncertain sound. At other times conscience is perplexed, and her answer is, _perhaps_, and _perhaps not_. When the woman hid Achimaas and Jonathan in the well, and said to Absalom's servants, "They passed on in haste" (2 Kings xvii. 17-21), did she do right in speaking thus to save their lives? A point that has perplexed consciences for centuries. A man's hesitation is sometimes subjective and peculiar to himself. It turns on a matter of fact, which others know full well, though he doubts; or on a point of law, dark to him, but clearly ruled by the consent of the learned. In such cases it is his duty to seek information from people about him, taking so much trouble to procure it as the importance of the matter warrants, not consulting ten doctors as to the ownership of one hen. But it may be that all due enquiries fail. The fact remains obscure; or about the law, doctors differ, and arguments conflict indecisively. What is the man to do? Take the _safe_ course: suppose there is an obligation, and act accordingly? This principle, put as a command, would make human life intolerable. It is, moreover, false, when so put, as we shall presently prove. Take the _easy_ course, and leave the obligation out of count? This principle is more nearly correct than the other: but it needs interpretation, else it may prove dangerously lax.