The tree's fruit
A good tree, out of the goodness of its heart, brings forth good fruit.
An evil tree brings forth evil fruit.
It is always safe to eat the fruit of a good tree.
It is never safe to eat of the fruit of a poisonous tree.
A fountain that issues forth pure water is always safe to drink.
A fountain with bitter waters should never be used to quench one's thirst.
A good man out of the goodness of his heart brings forth good things in abundance.
They are beneficial for all.
An evil man is never to be trusted.