”Your good resolutions must not make you proud, but humble and diffident; you carry a large sum of gold about you, take care not to meet any highwaymen. In this life there is nothing certain: we are in a continual warfare, and, therefore, ought to be on our guard day and night. We sail in a tempestuous sea that threatens us on every side, and in a poor leaky vessel: the devil, who aims at nothing less than our destruction, never ceases to increase the storm, to overwhelm us thereby, if he can; hence it was that the Apostle gave this precaution, even to the virtuous: ‘Let him that thinketh he standeth, take heed lest he fall’ (1 Cor. x.12)”
–Saint Jerome, Father and Doctor of the Church, Epistle to Saint Eustochium.