... The philosophy of St. Thomas stands founded on the universal conviction that eggs are eggs. The Hegelian may say that an egg is really a hen, because it is a part of an endless process of Becoming; the Berkeleian may hold that poached eggs only exist as a dream exists; since it is quite as easy to call the dream the cause of the eggs as the eggs the cause of the dream; the Pragmatist may believe that we get the best out of scrambled eggs by forgetting that they ever were eggs, and remembering only the scramble. But no pupil of St. Thomas needs to addle his brains in order adequately to addle his eggs; to put his head at any peculiar angle in looking at eggs, or winking the other eye, or squinting at eggs, or winking the other eye in order to see a new simplification of eggs. The Thomist stands in the broad daylight of the brotherhood of men, in their common consciousness that eggs are not hens or dreams or mere practical assumptions; but things attested by the Authority of the Senses, which is from God. Thus, even those who appreciate the metaphysical depth of Thomism in other matters have expressed surprise that he does not deal at all with what many now think the main metaphysical question; whether we can prove that the primary act of recognition of any reality is real. The answer is that St. Thomas recognized instantly, what so many other modern skeptics have begun to suspect rather laboriously; that a man must either answer that question in the affirmative, or else never answer any question, never ask any question, never even exist intellectually, to answer or to ask... a man can be a fundamental sceptic but he can never be anything else; certainly not a defender of fundamental scepticism. If a man feels that the movements of his own mind are meaningless, then his mind is meaningless, and he is meaningless; and it does not mean anything to attempt to discover his meaning. Most fundamental sceptics appear to survive, because they are not consistently sceptical and not at all fundamental... A man wrote to say that he accepted nothing but solipsism, and added that he often wondered it was not a more common philosophy. Now solipsism simply means that a man believes in his own existence, but not in anybody or anything else. And it never struck this simple sophist, that if his philosophy was true, there obviously were no other philosophers to profess it. To this question "Is there anything?" St. Thomas begins by answering "Yes"; if he began by answering "No", it would not be the beginning, but the end. That is what some of us call common sense.The whole bit about eggs comes about as a play on the latin -ens, "the present participle;" in philosophy it means something like "entity," something that exists. A few pages later, Chesterton points out how remarkable things follow from Aquinas' first step:
Perhaps it would be best to say emphatically (with a blow on the table), "There is an Is." That is as much monkish credulity as St. Thomas asks of us at the start. Very few unbelievers start by asking so little. And yet, upon this sharp pin point of reality, he rears by long logical processes that have never really been successfully overthrown, the whole cosmic system of Christendom.