To do the impossible is the beginning of faith, the beginning of greatness. Judaism is the art of the impossible.

A J Heschel Dinner address at  Lehman Institute - Conference ,  September 1963.* 

* The context of the above remark is interesting. In general H is giving a "recap" of the Religion and Race speech he gave in Chicago at the National Conference on Religion and Race in January '63. After speaking about the African - American problem ( in terms of those days ) H turned to the "problem of Soviet Jewry". Before that he spoke of the responsibility of communal leaders ( incl or esp. Rabbis ) for the well being of the destitute  individual, the  lonely wayfarer passing by in the village, later to be found dead in an adjacent field, as told in the Biblical story of "Egla Arufa". In the context of the need to take action for Soviet Jewry H recalls the situation of American Jews in 1942 in which mostly they kept quiet regarding the situation of the Jews of Europe. It is he says on the verge of impossible to speak out in times of war, and the vast majority of American Jews followed suit and did nothing, said nothing. Then come the sentences quoted above.