Clarification please...

["newbieonekenhobby <newbieonekenhobby@...>" <newbieonekenhobby@...>]

I started the "thought control/witnessing/monitoring" exercise, and 
I have a new question (sorry! I try to keep those at a minimum, but 
this one seems to be a pre-requisite to my practice) :

Talking about the thoughts, FB writes that :

- "observe your train of thought for five minutes, and make an 
attempt fo remember these thoughts" (p. 66).

- "it will be difficult for him (= the student) to remember all of 
them" (p. 67).

Does this mean that I not only have to observe the thoughts going 
through my mind (and remember them immediately after they arose), 
but that I have to remember all of them at the end of the 6-7-8 
minutes of the duration of the exercise ?
I did not find a clarification about this point.

Something else. I started re-reading the Theory and Kybalion 
simultaneously. The exercise is enriching indeed. I guess I'll have 
some questions in a few days :-(
...For example: given the principle of polarity, could we accept 
that fire and water are the same, but only different in terms of 
degree ? Same for electric / magnetic ? 

Best regards. Thanks for your patience.
New B