What is the saying about action and reaction?

Action and reaction are equal.

If you render anyone's life desolate—if you make him wretched and miserable, the action and reaction will be equal, and you will receive in the desolation experienced in your own person, just what you meted out to him. 

The natural tendency of your selfishness is to paralyse and contract the spirit until it becomes a mere pigmy in dimension, rendering its appearance more hideous [deformed and darkened spiritual body] than it otherwise would have been.

Impress on the children of earth this fact, that whatsoever they sow they shall reap, and you will do more to moralise and refine them than in any other way. 

The outer covering of the soul of the indwelling conscious self is composed exactly of such material as the sphere to which it gravitates. 

While on earth, your physical organisation is evolved from the various elements and connected therewith is the indwelling spirit. 

Acts of licentiousness, intense selfishness and a life in the purlieus of vice modify the character and texture of the latter and prepare it for a sphere corresponding with the life led here [in the world of spirits].

—Spirit Lucretus