Remember that the future is ...

Remember that the future is neither ours nor wholly not ours, so that we may neither count on it as sure to come nor abandon hope of it as certain not to be.
 Epicurus

Quotes from the same author

Of all the things which wisdom provides to make us entirely happy, much the greatest is the possession of friendship.
 Epicurus
It is not so much our friends' help that helps us, as the confidence of their help.
 Epicurus
Fortune seldom troubles the wise man. Reason has controlled his greatest and most important affairs, controls them throughout his life, and will continue to control them.
 Epicurus
Do not spoil what you have by desiring what you have not; remember that what you now have was once among the things you only hoped for.
 Epicurus
Is God willing to prevent evil, but not able? Then he is not omnipotent. Is he able, but not willing? Then he is malevolent. Is he both able and willing? Then whence cometh evil? Is he neither able nor willing? Then why call him God?
 Epicurus