Horace's Use
The original use seems to be in Horace's first book of Epistles: dimidium facti qui coepit habet: sapere aude, incipe ("He who has begun is half done: dare to know!"). It can also be translated as "Dare to be wise". The phrase forms the moral to a story where a fool (naive person) waits for the stream to stop before crossing it. "He who begins is half done. Dare to be wise. Make a beginning." is a loose translation. Horace's words suggest the value of human endeavour, of persistence in reaching a goal and of the need for effort in overcoming obstacles.
Read more about this topic: Sapere Aude