Do not hover always on the surface of things, nor take up suddenly, with mere appearances; but penetrate into the depth of matters, as far as your time and circumstances allow, especially in those things which relate to your profession.
You can’t tell how deep a puddle is until you step into it.
When the river is deepest it makes least noise.
What is in the marrow is hard to take out of the bone.
We have deep depth.
The music that can deepest reach, And cure all ill, is cordial speech.
I am deeply superficial
Love is a deep well from which you may drink often, but into which you may fall but once.
Deep within man dwell those slumbering powers; powers that would astonish him, that he never dreamed of possessing; forces that would revolutionize his life if aroused and put into action.
Those who can soar to the highest heights can also plunge to the deepest depths, and the natures which enjoy most keenly are those which also suffer most sharply.