St.John Bosco used to tell the boys who were under his care:
“Listen:There are two things the devil is deathly afraid of:fervent communions and frequent visits to Jesus in the Blessed Sacrament.
Do you want Our Lord to grant you many graces?Visit him often.
Do you want Him to grant you only a few?Visit him 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 Jesus’ feet.
Do you want to be overcome by the devil?Give up visiting Jesus.
Visiting the Blessed Sacrament is essential,my dear boys,if you want to overcome the devil.Therefore make frequent visits to Jesus.If you do that,the devil will never prevail against you.”
Several saints are known to have exercised demons from the possessed,or banished evil spirits in apparitions,through the consecrated Host of the Blessed Sacrament.St.Bernard,St.John of the Cross,St.Francis de Sales,St.Peter of Verona,and others testified to the power of Our Lord’s Eucharistic presence.