It is asserted but not proved.

What makes all doctrines plain and clear?
About two hundred pounds a year.
And that which was proved true before,
Prove false again? two hundred more. [ Butler ]

A quill hath proved the noblest gift to man. [ Byron ]

I took him for a worm, but he proved a serpent. [ Proverb ]

Love is not love
Which alters when it alteration finds,
Or bends with the remover to remove;
No! it is an ever-fixed mark,
That looks on tempests and is never shaken;
It is the star to every wandering bark,
Whose worth'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. [ William Shakespeare ]

Nor is he the wisest man who never proved himself a fool. [ Tennyson ]

Trust him with little who, without proofs, trusts you with everything, or,
When he has proved you, with nothing. [ Lavater ]

How happy are the pessimists! What joy is theirs when they have proved there is no joy. [ Marie Ebner-Eschenbach ]

Men declare their love before they feel it; women confess theirs only after they have proved it. [ Latena ]

We do not believe immortality because we have proved it, but we forever try to prove it because we believe it. [ James Martineau ]

Genius is rarely found without some mixture of eccentricity, as the strength of spirit is proved by the bubbles on its surface. [ Mrs. Balfour ]

It is generally admitted, and very frequently proved, that virtue and genius, and all the natural good qualities which men possess, are derived from their mothers. [ T. Hook ]

Miss Edgeworth and Mme. de Stael have proved that there is no sex in style; and Mme. la Roche Jacqueline, and the Duchesse d'Angouleme have proved that there is no sex in courage. [ Colton ]