Love is not love which alters when it alteration finds, Or bends with the remover to remove. O, no! it is an ever-fixèd mark, That looks on tempests and is never shaken; It is the star to every wandering bark; Whose wirth's unknown, although his height be taken. Love's not Time's fool, though rosy lips and cheeks within his bending sickle's compass come; Love alters not with his brief hours and weeks, But bears it out even to the edge of doom.
If this be error, and upon me proved,
I never writ, nor no man ever loved.

Let me not to the marriage of true minds, W. Shakespeare