Do not look back, 
No one knows how the world ever began. 
Do not fear the future, Nothing lasts forever. 
If you dwell on the past or future, 
You will miss the moment.

Rumi (1207-1273), Jalāl ad-Dīn Muhammad Rūmī-more popularly simply as Rumi was a 13th-century Persian poet, faqih, Islamic scholar, theologian, and Sufi mystic originally from Greater Khorasan.