Sourced
The journey of a thousand li commences with a single step.
A li is about half a kilometre — "a thousand miles" is a later rounding.
Source: Tao Te Ching, ch. 64, tr. James Legge
Authors / Lao Tzu
Lao Tzu may be a real person, a composite, or a legend; the Tao Te Ching is his only text. Translations differ wildly, so we cite the chapter and the translation.