Seize the very first possible opportunity to act on every resolution you make, and on every emotional prompting you may experience in the direction of the habits you aspire to gain.

(Five) thinkers since Galileo, each informing his successor of what discoveries his own lifetime had seen achieved, might have passed the torch of science into our hands as we sit here in this room. Indeed, for the matter of that, an audience much smaller than the present one, an audience of some 5 or 6 score people, if each person in it could speak for his own generation, would carry us away to the black unknown of the human species, to days without a document or monument to tell their tale.

... if we take the universe of 'fitting,' countless coats 'fit' backs, and countless boots 'fit' feet, on which they are not practically fitted; countless stones 'fit' gaps in walls into which no one seeks to fit them actually. In the same way countless opinions 'fit' realities, and countless truths are valid, tho no thinker ever thinks them.

We never fully grasp the import of any true statement until we have a clear notion of what the opposite untrue statement would be.

Plasticity, then, in the wide sense of the word, means the possession of a structure weak enough to yield to an influence, but strong enough not to yield all at once. Each relatively stable phase of equilibrium in such a structure is marked by what we may call a new set of habits.

So it is with children who learn to read fluently and well: They begin to take flight into whole new worlds as effortlessly as young birds take to the sky.

Man, biologically considered ... is simply the most formidable of all beasts of prey, and, indeed, the only one that preys systematically on its own kind.