Oil and water don’t mix.

(Certain materials or people cannot be combined.)

Once a thief, always a thief.

(It’s difficult for a person to his or her ways. A person who has stolen in the past is likely to commit the crime again.)

Once bitten, twice shy.

(After having one bad experience with something, a person is probably going to be very careful the next time a similar experience arises. This proverb is often applied to romantic relationships.)

One good turn deserves another.

(If someone does something nice for you, you should try to return the favor for that person or someone else.)

One man’s junk is another man’s treasure.

(What one person considers to be worthless, another person might consider to be valuable. Value depends on the person who evaluates the object.)

One rotten apple will spoil the whole barrel.

(One bad person or thing will ruin an entire group through contact or proximity.)

Only the good die young.

(Young people who die early are good people.)

Opportunity knocks only once.

(You get one chance in life to take advantage of certain opportunities–wealth, power, love, prestige, fame, etc.)

Out of sight, out of mind.

(If you don’t see something, you and others won’t think about it.)

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