Bring it All Inwards

So resolve yourselves. It's not just by sitting with your eyes closed that you develop wisdom. Eyes, ears, nose, tongue, body and mind are constantly with us, so be constantly alert. Study constantly. Seeing trees or animals can all be occasions for study. Bring it all inwards. See clearly within your own heart. If some sensation makes impact on the heart, witness it clearly for yourself, don't simply disregard it.

by Ajahn Chah