"Teach" is an intransitive verb.

When do I learn, and why?

1. When I'm required to (reluctantly).

2. When I need to know for reasons of my own.

3. When I'm curious about the subject.

What do I learn best from?

(in order of increasing effectiveness)

1. From listening to someone else talk.

2. From reading (a) a beautifully written book; or (b) a badly written book. The latter is more effective. (No pain, no gain.)

3. From paraphrasing in my own words.

4. From using what I have nominally learned.

5. From trying to explain it to others. In order of increasing stress,
   • ``brainstorming'' with enthusiastic peers
   • writing papers on my research
   • writing textbooks on well-known subjects
   • lecturing in front of a captive audience
   • speaking in front of a voluntary audience
   • arguing with peers who think I am wrong

   What would help most?

   My answer:

   a universal manual

   with an

   omniscient Index.