### "What has been affirmed without proof can also be denied without proof."

Euclid of Alexandria is **the most prominent mathematician of antiquity** best known for his treatise on mathematics “The Elements”. Euclid is often referred to as the “founder of geometry” or the “father of geometry”. He was active in Alexandria during the reign of Ptolemy I (323–283 BC). His Elements is one of the most influential works in the history of mathematics, serving as the main textbook for teaching mathematics (especially geometry) from the time of its publication until the late 19th or early 20th century. In the Elements, Euclid deduced the theorems of what is now called Euclidean geometry from a small set of axioms. Euclid also wrote works on perspective, conic sections, spherical geometry, number theory, and mathematical rigor.

Little is known of Euclid’s life except that he taught in Alexandria. He was likely born c. 325 BC, although the place and circumstances of both his birth and death are unknown.

**What is Euclid known for? **

Euclid is known as the “father of geometry”. His most famous work is his collection of 13 books, dealing with geometry, called **The Elements**. They are said to be “the most studied books apart from the Bible”.

- Books 1-6 deal with plane geometry
- Books 7-9 deal with number theory
- Book 10 deals with Eudoxus’s theory of irrational numbers
- Books 11-13 deal with solid geometry

A common misconception is that Euclid invented all concepts of geometry. This is certainly not so, as he really only pulled together ideas and developed them as his own within a textbook. However, he definitely developed the discipline in this regard, making it a concrete, organized study that people could learn from by following his written work.

He is also famous for his theories on other parts of life: in **Optiks**, he discusses perspective and gives insight to how we view the world through our eyes.

With geometric principles, other mathematicians in later centuries were able to develop upon his work. In this regard, he is understood to be the Father of Geometry since he paved the way for so many future thinkers to expand upon his organized ideas.