I proceed to examples and developments of the doctrine, chiefly insisted upon in the former letter. I draw them chiefly from Mr Combe, premising, that they exactly coincide with views which you cannot but remember to have heard me advance, before I had read his book on _the constitution of man_. It is a law of the animal creation, that not only the natural but even the acquired qualities are transmitted by parents to their offspring; and man, as an organized being, is subject to laws similar to those which govern the organization of the lower animals. ‘Children,’ says Dr Pritchard, ‘resemble in feature and constitution both parents; but I think more generally the father.’ Changes produced by external causes in the constitution and appearance of the individual are temporary; and, in general, acquired characters are transient, terminating with the individual, and having no influence on the progeny. The mental development of the Circassian race is known to be of the highest order. The nobles of Persia are children of Circassian mothers, and they are remarkable, in that country, for their mental and corporeal superiority over the other classes. Every one acquainted with the condition of our southern slaves, well understands the obvious fact, that the mulattoes are much superior, in quickness and capability of acquiring and retaining knowledge, to the negroes. The Indian half-breeds are remarkable for the immediate ascendency, which they acquire in their tribes over the full-blooded Indians. In oriental India, the intermarriages of the Hindoos with Europeans have produced an intermediate race much superior to the natives, and destined, it is already predicted, to be the future sovereigns of India. In fact, physiology has deduced no conclusion more certain, than that, in ordinary cases, the temperament and intellect of the children are a compound of that of their parents. Of this I might produce innumerable instances from history of the Alexanders, Cæsars, and Antonines, the distinguished great and wise, of ancient and modern times; and equally, in the opposite direction, in the Neros and Caligulas, the depraved and abandoned of all ages and countries, where observation has been able to trace their parentage.