11 I have written these things in order to show that whoever is disposed to maintain and vindicate any one of these four theories of the soul's origin, must bring forward, either from the Scriptures received into ecclesiastical authority, passages which do not admit of any other interpretation -- as the statement that God made man -- or reasonings founded on premises so obviously true that to call them in question would be madness, such as the statement that none but the living are capable of knowledge or of error; for a statement like this does not require the authority of Scripture to prove its truth, as if the common sense of mankind did not of itself announce its truth with such transparent cogency of reason, that whoever contradicts it must be held to be hopelessly mad. If any one.is able to produce such arguments in discussing _the very obscure question of the soul's origin, let him help me in my ignorance; but if he cannot do this, let him forbear from blaming my hesitation on the question.
Source: Letters (New Advent)