Now, in man, the very reverse of this appears to be the case; for he has so few distinct and characteristic marks which hold true of all his species, that philosophers in all ages have found it a task of infinite difficulty to give him a definition.  Hence one has defined him to be a featherless biped, a definition which is equally applicable to an unfledged fowl:  another to be an animal which forms opinions, than which nothing can be more inaccurate, for a very small number of the species form opinions, and the remainder take them upon trust, without investigation or inquiry.

“Again, man has been defined to be an animal that carries a stick:  an attribute which undoubtedly belongs to man only, but not to all men always; though it uniformly characterises some of the graver and more imposing varieties, such as physicians, oran-outangs, and lords in waiting.

“We cannot define man to be a reasoning animal, for we do not dispute that idiots are men; to say nothing of that very numerous description of persons who consider themselves reasoning animals, and are so denominated by the ironical courtesy of the world, who labour, nevertheless, under a very gross delusion in that essential particular.

“It appears to me that man may be correctly defined an animal, which, without any peculiar or distinguishing faculty of its own, is, as it were, a bundle or compound of faculties of other animals, by a distinct enumeration of which any individual of the species may be satisfactorily described.  This is manifest, even in the ordinary language of conversation, when, in summing up, for example, the qualities of an accomplished courtier, we say he has the vanity of a peacock, the cunning of a fox, the treachery of an hyaena, the cold-heartedness of a cat, and the servility of a jackal.  That this is perfectly consentaneous to scientific truth, will appear in the further progress of these observations.

“Every particular faculty of the mind has its corresponding organ in the brain.  In proportion as any particular faculty or propensity acquires paramount activity in any individual, these organs develope themselves, and their development becomes externally obvious by corresponding lumps and bumps, exuberances and protuberances, on the osseous compages of the occiput and sinciput.  In all animals but man, the same organ is equally developed in every individual of the species:  for instance, that of migration in the swallow, that of destruction in the tiger, that of architecture in the beaver, and that of parental affection in the bear.  The human brain, however, consists, as I have said, of a bundle or compound of all the faculties of all other animals; and from the greater development of one or more of these, in the infinite varieties of combination, result all the peculiarities of individual character.

“Here is the skull of a beaver, and that of Sir Christopher Wren.  You observe, in both these specimens, the prodigious development of the organ of constructiveness.