If you do these things, "the devil will never prevail against you."
In particular, he would frequently relate to the boys how to stay protected against the devil. Below is his advice and, if followed faithfully, Bosco claimed “the devil will never prevail against you.”
Listen: there are two things the devil is deathly afraid of: Fervent Communions and frequent visits to the Blessed Sacrament.
Do you want many graces? Visit Him often.
Do you want Him to grant you only a few? Visit Him but seldom.
Do you want the devil to attack you? Rarely visit the Blessed Sacrament.
Do you want the devil to flee from you? Visit Jesus often.
Do you want to overcome the devil? Take refuge at the feet of Jesus.
Do you want to be overcome by the devil? Give up visiting Jesus.
Visiting Jesus in the Blessed Sacrament is essential … if you want to overcome the devil.
Therefore make frequent visits to Jesus.
If you do that, the devil will never prevail against you.