§151

'Know' might be used in saying 'Now I know!' (You might be pondering how to continue a series and then exclaim 'Now I know!' (now I know how to continue the series))
If we imagine someone (B) watching someone else (A) writing out a series and saying, 'now I can go on!' when they have worked out the rule it seems that understanding is something that occurs in a moment.

But what occurs?
- Various things might occur.
  - B might try out various algebraic formulae and then have it confirmed that one fits the series.
  - B might ask himself the difference between each step in the series and find a pattern.
  - B might watch A writing out the series and say, 'Yes. I know that series.'
  - B might have a certain feeling.