Leonhard Euler

AD 1707 - AD 1783

Saint Petersburg

Enlightenment

Life

An exceptionally prolific author across analysis, number theory, mechanics, astronomy, and early graph problems. He introduced or popularized major notation and continued working by dictation with family and assistants after losing most of his sight.

In one line

Read Euler, read Euler, he is the master of us all.

Decisive moments

AD 1735

The Basel problem — finding π in a sum

Saint Petersburg

He obtained 1 + 1/4 + 1/9 + … = π²/6. Later standards sharpened parts of the argument, but the result and methods were transformative.

AD 1748

Connecting complex exponentials and trigonometry

The Introductio systematically developed relations between complex exponentials and trigonometry; e^(iπ)+1=0 is one special case.

AD 1771

Collaborative work after loss of sight

After losing nearly all sight, he used memory and dictation and continued research with help from family, assistants, and scribes.

If this person hadn't existed

This is a thought experiment about influence, not a verified historical fact.

Euler did not single-handedly create eighteenth-century mathematics. Working through the Bernoulli network, academies, family, and assistants, he made notation and methods reusable across fields and greatly lowered the cost of connecting ideas.