Who knows the source for the following saying please? "There is no evil without good." I have seen Bereshit Rabbah cited without a page number.
Here is what you are referring to: The Jewish teaching that the Evil Inclination is necessary for all achievement. The Midrash says [Genesis Rabbah 9:7] :
Nachman said, in Rav Shmuel's name: “And, behold, it was very good” refers to the Evil Inclination. Can then the Evil Inclination [then] be “very good”? That would be extraordinary!
Yes, [because] without the Evil Inclination, no man would build a house, take a wife, beget a family, and engage in work. So said [King] Solomon [in Ecclesiastes]: “And I saw that all labor and all achievement in work was the result of man's envy and rivalry with his neighbor.” [Eccl. 4:4]