Who said: "instead of trying to reproduce exactly what i have before my eyes, i use color more arbitrarily so as to express myself forcibly . . i have tried to express the terrible passions of humanity by means of red and green . ."?

Vincent van Gogh.

Explanation:

In his letter to his younger brother Theo van Gogh, noted painter Vincent van Gogh mentioned how he worked on the painting of a one Mr. Patience Escalier and a "drawing of the postman Rollin".

The letter sent on August 11, 1888 describes the paintings he had made and sent it over to Theo. In the second stanza of the letter, he explicitly explained the ways he had these portraits made. He explained "instead of trying to reproduce exactly what I have before my eyes, I use color more arbitrarily, in order to express myself forcibly". He then went on to explain what he would have liked to do with his "portrait of an artist friend, a man who dreams great dreams". Revealing his plans on how this new 'in-process' painting will look like, van Gogh continued to give an explanation of his portraits.

well for some you have to do on your own on a paper but yeah