Institutio Oratoria

But reason by itself would help us but little and would be far less evident in us, had we not the power to express our thoughts in speech; for it is the lack of this power rather than thought

The construction of a soft lair, the weaving of nests, the hatching and rearing of their young, and even the storing up of food for the coming winter, together with certain other achievements which we cannot imitate, such as the making of honey and wax, all these perhaps indicate the possession of a certain degree of reason; but since the creatures that do these things lack the gift of speech they are called dumb and unreasoning beasts.

Finally, how little the heavenly boon of reason avails those who are born dumb. If therefore we have received no fairer gift from heaven than speech, what shall we regard as so worthy of laborious cultivation, or in what should we sooner desire to excel our fellow-men, than that in which mankind excels all other living things?