If you are thinking of ...

If you are thinking of nything with dependence upon it, there is a motive of curiosity, or pleasure, or success, and though the thinking will help towards satisfaction you will still be in bondage. There is no harm in this, but the higher samadhi, without such motives, is best.
 Ernest Wood

Quotes from the same author

It is not healthy to be thinking all the time. Thinking is intended for acquiring knowledge or applying it. It is not essential living.
 Ernest Wood