**William Kingdon Clifford**, an English mathematician and philosopher, was born in the city of Exeter on May 4, 1845. He died at a young age of 33 on March 3, 1879 in the Autonomous Region of Madeira. In addition to being a mathematician, he was a gymnast, a writer of children's stories (such as the *The little people*) and renowned declaimer, winning several awards.

Named after him are Clifford algebras, which are associative algebras of importance in mathematics, in particular in quadratic form and orthogonal group theory and physics.

Based on Hermann Grassmann's work, he introduced what is now called geometric algebra, a special case of Clifford algebra, with significant applications in mathematical physics, geometry and computation. Geometric algebra operations have the effect of mirroring, rotating, translating, and mapping geometric objects being modeled to new positions.

Clifford began his career early at age 15 at King's College in London and later at Trinity College (1863) in Cambridge, where he has always excelled in mathematics, classics, English literature and gymnastics. He was elected fellow in Trinity in 1868 and two years later went to Sicily to observe an eclipse, a voyage in which he narrowly escaped death in a wreck.

Wrote the article *On the space-theory of matter* (1870) on non-Euclidean geometry, in which he showed that energy and matter were simply different types of curves in space. This work was important for the elaboration of relativity theory by Albert Eintein. He became professor of applied mathematics and mechanics at University College, London (1871).

In 1874, he was elected Member of the Royal Society (*Fellow of the Royal Society*), an honorary title granted to notable scientists. In 1876 his health began to worsen and the following year he was traveling through Mediterranean countries, researching and writing memoirs.

He collapsed, probably due to overwork because he taught and administered during the day and wrote at night. He even continued his activities for another 18 months, but his health did not improve. She went to Madeira to try to recover, but died of tuberculosis after a few months, leaving a widow with two children.

Clifford was the first to suggest that gravitation could be a manifestation of an underlying geometry. Born eleven days later, Albert Einstein would continue to develop the geometric theory of gravity suggested by Clifford nine years earlier. Clifford and his wife are buried in London's Highgate cemetery, north of Karl Marx's grave, and near the graves of George Eliot and Herbert Spencer.

Clifford had many of his works published after his death, such as *Elements of dynamics*, vol II (1878), *Lectures and essays* and *Seeing and thinking* (1879) and *Common sense of the exact sciences* (1885), this completed by Pearson.