Born on this day in Ulm, Germany, Albert Einstein (1879-1955) understood what counted and was the embodiment of genius. "The important thing," he said, "is to not stop questioning."

As a child, he loved numbers, but had trouble memorizing facts. He struggled and was expelled from school, but always was passionately curious.

Upon college graduation, the man who revolutionized modern thinking was unable to get an academic position and worked as a patent office clerk. On his daily walks to and from work, he thought about physics, exploring the connection between light, space, and time.

In 1905, annus mirabilis, the miracle year, Einstein, 26, finished his paper, On the Electrodynamics of Moving Bodies. He applied his Special Relativity to objects moving at constant speeds with the famous equation: E=mc².

Einstein proved that energy (E) and mass (m) are equivalent. Mass can be converted to energy and vice versa by the speed of light (c) -- 186,000 miles per second -- squared. This means a small amount of matter can be transformed into a huge amount of energy. By 1915, Einstein used the formula to develop his general Theory of Relativity, which helped us better understand the universe.

"To raise new questions, new possibilities, to regard old problems from a new angle requires a creative imagination and marks the real advances in science," he believed.

A pacifist who celebrated nature, Einstein had a halo of wild hair and played the violin with passion. He used his imagination to discover and his heart to translate these discoveries into hope. "Strive not to be a success, but rather to be of value," he said.

His discoveries, said Beth Harpaz of the Associated Press, "laid the groundwork for 20th century technologies ranging from television to space travel." Time magazine, in naming his the Person of the 20th Century, called him a "genius, political refugee, humanitarian, locksmith of the mysteries of the atom and the universe."

More EINSTEIN Quotations

What really counts is not always obvious.