"Necessity Is the Mother of Invention"

This idiomatic expression means that if you want to or need to do something very much, you will think of a way to do it. 


For example: Since we don't have any gift-wrapping paper, let's use the old newspaper to wrap the present. After all, necessity is the mother of invention.

This idea is exhibited in the story of "The Crow and the Pitcher" by Aesop,  a Greek storyteller from the 6th Century B.C.:


"A crow, perishing with thirst, saw a pitcher, and, hoping to find water, flew to it with great delight. When he reached it, he discovered to his grief that it contained so little water that he could not possibly get at it. He tried everything he could think of to reach the water, but all his efforts were in vain. At last he collected as many stones as he could carry and dropped them one by one with his beak into the pitcher, until he brought the water within his reach, and thus saved his life."

Source:

Aesop's Fables
Copyright 1881
Translator: unknown
WM. L. Allison, New York
Illustrator: Harrison Weir, John Tenniel, Ernest Griset, et.al.