That which can be lost cannot be deemed riches.
The vine that has grown old on an old tree falls with the ruin of that tree, and through that bad companionship must perish with it.
Iron rusts from disuse; water loses its purity from stagnation... even so does inaction sap the vigor of the mind.
When you are alone you are all your own.
Nothing is hidden under the sun.
Just as iron rusts from disuse, and stagnant water putrefies, or when cold turns to ice, so our intellect wastes unless it is kept in use.