Bolzano,Bernard (1781-1848), logician 
and mathematician, devoted an extensive part of his comprehensive
presentation of logic, Wissenschaftslehre, to the subject 
of heuristic (vol 3, pp. 293,-055). He writes about this
part of his work; "I do not think at all that I am able
to present here any procedure of investigation that was
not perceived long ago by all men of talent; and I do not
promise at all that you can find here anything quite new
of this kind. But I shall take pains to state in clear words
the rules and ways of investigation which are followed
by all able men, who in most cases are not even conscious
of following them. Although I am free from the illusion
that I shall fully succeed even in doing this, I still hope
that the little that is presented here may please some
people and have some application afterwards."