The development occurs through reciprocal give-and-take, the teacher taking but not being afraid also to give.

Without initiation into the scientific spirit one is not in possession of the best tools which humanity has so far devised for effectively directed reflection. One in that case not merely conducts inquiry and learning without the use of the best instruments, but fails to understand the full meaning of knowledge.

Written symbols are even more artificial or conventional than spoken; they cannot be picked up in accidental intercourse with others. In addition, the written form tends to select and record matters which are comparatively foreign to everyday life.

We have three approaches at our disposal: the observation of nature, reflection, and experimentation. Observation serves to assemble the data, reflection to synthesise them and experimentation to test the results of the synthesis. The observation of nature must be assiduous, just as reflection must be profound, and experimentation accurate. These three approaches are rarely found together, which explains why creative geniuses are so rare.

Selection aims not only at simplifying but at weeding out what is undesirable.

No system has ever as yet existed which did not in some form involve the exploitation of some human beings for the advantage of others.

In fact, the human young are so immature that if they were left to themselves without the guidance and succor of others, they could not acquire the rudimentary abilities necessary for physical existence.