Psychology teaches us at every step that though two types of activity can have the same external manifestation, whether in origin or essence, their nature may differ most profoundly.

The specifically human capacity for language enables children to provide for auxiliary tools in the solution of difficult tasks, to overcome impulsive action, to plan a solution to a problem prior to its execution, and to master their own behavior.

What children can do with the assistance of others might be in some sense even more indicative of their mental development than what they can do alone

There is reason to believe that voluntary activity, more than highly developed intellect, distinguishes humans from the animals which stand closest to them.

Psychology teaches us at every step that though two types of activity can have the same external manifestation, whether in origin or essence, their nature may differ most profoundly.

By giving our students practice in talking with others, we give them frames for thinking on their own.

A word devoid of thought is a dead thing, and a thought unembodied in words remains a shadow.