"But rarely does the idea present itself alone.
"One thought almost always produces the manifestation of similar thoughts, which group themselves around the first idea as birds of the same race direct their flight toward the same country.
"Thought is the manifestation of the intellectual life; it palpitates in the brain of men as does the heart in the breast.
"It is thought which distinguishes men from animals, who have only instinct to guide them.
"It can be admitted, however, that this instinct is a kind of obscure thought for these inferior beings, from which reflection is eliminated, or, at least, reveals itself only as a vassal of material appetite.
"But with creatures who have intelligence, thought is a superior faculty, which aids the soul to free itself from the bondage of vulgar and limited impressions.
"When perception, memory, and thought unite to form judgment, activity of mind will become necessary, in order to accelerate the production of ideas in extending the field of imagination.
"Moral inertia is the most deplorable of all defects; it retards intellectual growth and hinders the development of personality.
"It is, in this understanding, the enemy of common sense, for it will admit voluntarily a reasoning power, existing per se, rather than make the necessary effort which will set free the truth and constitute an individual opinion.
"Vulgarity is, then, almost always the sign of mental sloth.