Man is largely a creature of habit, and many of his activities are more or less automatic reflexes from the stimuli of his environment.

.. every step of the upward way is strewn with wreckage of body, mind, and morals.

Adolescence is when the very worst and best impulses in the human soul struggle against each other for possession.

The teens are emotionally unstable and pathic. It is a natural impulse to experience hot and perfervid psychic states, and it is characterized by emotionalism. We see here the instability and fluctuations now so characteristic. The emotions develop by contrast and reaction into the opposite.

This splendid subject [mathematics], queen of all exact sciences, and the ideal and norm of all careful thinking.

Man is largely a creature of habit, and many of his activities are more or less automatic reflexes from the stimuli of his environment.

The man of the future may, and even must, do things impossible in the past and acquire new motor variations not given by heredity.