Pope John XXIII was always trying to sanctify himself, even as a young boy. The following is an excerpt from his journal, during a Holy Week retreat, when he was the Papal Representative in France (1945).
"In order to simplify everything, I shall bear in mind the theological and cardinal virtues. The first cardinal virtue is prudence. This is what Popes, Bishops, king and commanders have found difficult, and it is in this that they frequently fail. It is the characteristic quality of the diplomat, so I must cultivate it with particular care. Every evening I must examine myself strictly on this point. My ready tongue often betrays me into saying far too much. Beware, beware! Know how to preserve silence, how to speak with moderation, how to refrain from judging people and their attitudes, except when this is an obligation imposed by Superiors, or for grave reasons.This is a good lesson for all of us. It is always to say less than more. You will not regret saying less. It is always a good idea to think, and pray before speaking. Think of all the saints. They were very prudent in speech.
On every occasion say less rather than more and always be afraid of saying too much, remembering St. Isidore of Seville's praise to St. Fulgentius. And be particularly careful to preserve charity. This is my Rule".
- Journal of a Soul