The future mathematician ... should solve problems, choose the problems which are in his line, meditate upon their solution, and invent new problems. By this means, and by all other means, he should endeavor to make his first important discovery: he should discover his likes and dislikes, his taste, his own line.
George PolyaSuccess in solving the problem depends on choosing the right aspect, on attacking the fortress from its accessible side.
George PolyaA GREAT discovery solves a great problem but there is a grain of discovery in any problem.
George Polya