The violence of love is as much to be dreaded as that of hate.
 Henry David Thoreau, A Week on the Concord and Merrimack Rivers (1849). copy citation

Context

“He who can pronounce my name aright, he can call me, and is entitled to my love and service. Yet reserve is the freedom and abandonment of lovers. It is the reserve of what is hostile or indifferent in their natures, to give place to what is kindred and harmonious. The violence of love is as much to be dreaded as that of hate. When it is durable it is serene and equable. Even its famous pains begin only with the ebb of love, for few are indeed lovers, though all would fain be. It is one proof of a man’s fitness for Friendship that he is able to do without that which is cheap and passionate.” source