Lucius Annaeus Seneca - All the greatest blessings are a source of anxiety, and...

All the greatest blessings are a source of anxiety, and at no time should fortune be less trusted than when it is best; to maintain prosperity there is need of other prosperity, and in behalf of the prayers that have turned out well we must make still other prayers. For everything that comes to us from chance is unstable, and the higher it rises, the more liable it is to fall. Moreover, what is doomed to perish brings pleasure to no one; very wretched, therefore, and not merely short, must the life of those be who work hard to gain what they must work harder to keep. By great toil they attain what they wish, and with anxiety hold what they have attained; meanwhile they take no account of time that will never more return.