Don't be reckless with other people's hearts. Don't put up with people who are reckless with yours.

Never give all the heart, for love
Will hardly seem worth thinking of
To passionate women if it seem
Certain, and they never dream
That it fades out from kiss to kiss;
For everything that's lovely is
But a brief, dreamy, kind delight.
O Never give the heart outright,
For they, for all smooth lips can say,
Have given their hearts up to the play.
And who could play it well enough
If deaf and dumb and blind with love?
He that made this knows all the cost,
For he gave all his heart and lost.

Do not give in too much to feelings. A overly sensitive heart is an unhappy possession on this shaky earth.

Beware what you set your heart upon. For it surely shall be yours.

Merry hearts are vulnerable to death, don't be over-joyed to the state of oblivion, lest the enemy poison your meal.

Don't trust the heart, it wants your blood.

You can’t give your heart to a wild thing.

Let those who would keep two youthful hearts asunder, beware of music.

Trust no one until you are very sure of the heart to which you open your heart. Learn to mistrust every one; take every precaution for the sake of the love which does not exist as yet.

Quick-loving hearts ... may quickly loathe.

I counsel thee, shut not thy heart nor thy library

When you betray your own heart, you suffer for life. Always be true to your heart!

I gave him my heart, and he took and pinched it to death; and flung it back to me.

I gave him my heart, and he took and pinched it to death; and flung it back to me. People feel with their hearts, Ellen, and since he has destroyed mine, I have not power to feel for him.