知 - Zhi1 - Know, Knowledge

A piece of calligraphy we bought in Xian:

You read it right to left, top to bottom. This is what it says:

知足常樂 - Zhi1 Zu2 Chang2 Le4 - Know Enough Always Happy

The meaning is something along the lines of “If you can be content with what you have, you’ll always be happy”. But I’ve also seen people try to capture the essence with “Think not on what you lack as much as on what you have”, “If we are content with the things that surround us, we will feel happy”, “A contented mind is a perpetual feast”, “Happiness consists in contentment”, and simply “Content is happiness”.