After a certain amount of effort in many of these cases, further exertion is injurious, the mind or receptive power seems to be seized--as if nauseated--with spasmodic rejections.

In such a case pass the question by, but on going to bed, think it over and _will_ to understand it on the morrow.

It will often suffice to merely desire that it shall recur in more intelligible form--in which case, _nota bene_--if let alone it will obey.

This is as if we had a call to make tomorrow, when, as we know, the memory will come at its right time of itself, especially if we employ Forethought or special pressure.
When I reflect on what I once endured from this cause, and how greatly it could have been relieved or alleviated, I feel as if I could beg, with all my heart, every student or teacher of youth to seriously experiment on what I set forth in this book.

It is also to be observed, especially by metaphysicians and mental philosophers, that a youth who has shown great indifference to, let us say mathematics, if he has manifested an aptitude for philosophy or languages, will be in all cases certain to excel in the former, if he can be brought to make a good beginning in it.