$T$. $S$. $Eliot$, Introduction to Dante's Inferno: " Hell is a place where nothing connects with nothing. "
$Johann$ $von$ $Neumann$: " In mathematics you don't understand things, You just get used to them. "
$A$. $A$. $Zinoviev$: " Where there are problems, there is life. "
$P$. $R$. $Halmos$: "I do believe that problems are the heart of mathematics, and I hope that as teachers, in the classroom, in seminars, and in the books and articles we write, we will emphasize them more and more, and that we will train our students to be better problem-posers and problem-solvers than we are. "
$Shahrooz$: " Physics is mirror front of universe, but mathematics is the rules of reflection. "