Johann Carl Friedrich Gauss (April 30, 1777 - February 23, 1855) was a German mathematician who contributed significantly to many fields, including number theory, algebra, statistics, analysis, differential geometry, geodesy, geophysics, mechanics, electrostatics, astronomy, matrix theory, and optics. Sometimes referred to as the Princeps mathematicorum and "greatest mathematician since antiquity", Gauss had an exceptional influence in many fields of mathematics and science and is ranked as one of history's most influential mathematicians. He was an ardent perfectionist and a hard worker. He was never a prolific writer, refusing to publish work which he did not consider complete and above criticism. When he died, in 1855 at the age of 77, his brain was preserved and was studied by Rudolf Wagner who found its mass to be 1,492 grams (slightly above average). Highly developed convolutions were also found, which in the early 20th century was suggested as the explanation of his genius.