Great things are not accomplished overnight; great deeds take a long time. A proverb. A takes a long time to write a successful novel, but don't worry; Rome wasn't built in a day, as the saying goes.
ROME WASN'T BUILT IN A DAY
Meaning of ROME WASN'T BUILT IN A DAY in English
American idioms English vocabulary. Английский словарь американских идиом. 2012