We must endeavor never to act from the impulse of nature, interest, inclination, temper, or caprice, but always from the pure and single motive of doing the will of God, and accustom ourselves to this in all things. -St. Vincent de Paul
It was the great and only anxiety of this Saint not to undertake anything to which he might not seem impelled by the Divine will. And so he made it a rule never to engage by himself in new enterprises even for the glory of God, which he had so much at heart, but always waited until the will of the Lord should be manifested to him by Superiors, or at least by the opinion of others, or the prayers which he made or asked; for his humility made him always distrust his own light, and fear to be deceived.
This most important truth was well understood by St. Catherine of Genoa, who spoke thus on the subject: “There is no pest more malignant than that of self-will, which is so subtle, so malicious, so deeply seated, which conceals itself in so many ways, and defends itself by so many reasons, that it seems indeed a demon. When it cannot gain direct obedience, it knows well how to win its way in some other form, and under various excuses and pretexts, such as health, necessity, charity, justice, perfection, suffering for God, giving good example, finding spiritual consolation, condescending to the weakness of others, while we are all the while seeking, contriving, and cherishing our own interests.”
Text from A Year With the Saints (New York: P.J. Kenedy & Sons, 1891).