Matthew 10:1

"And when He had called unto Him," it saith, "His twelve disciples, He gave them power against unclean spirits, to cast them out, and to heal all manner of sickness, and all manner of disease." Still the Spirit was not yet given. For "there was not yet," it saith, "a Spirit, because that Jesus was not yet glorified." How then did they cast out the spirits? By His command, by His authority. And mark, I pray thee, also, how well timed was the mission. For not at the beginning did He send them; but when they had enjoyed sufficiently the advantage of following Him, and had seen a dead person raised, and the sea rebuked, and devils expelled, and a paralytic new-strung, and sins remitted, and a leper cleansed, and had received a sufficient proof of His power, both by deeds and words, then He sends them forth: and not to dangerous acts, for as yet there was no danger in Palestine, but they had only to stand against evil speakings. However, even of this He forewarns them, I mean of their perils; preparing them even before the time, and making them feel as in conflict by His continual predictions of that sort.

A kind and merciful Lord and Master does not envy His servants and disciples a share in His powers. As Himself had cured every sickness and disease, He imparted the same power to His Apostles. But there is a wide difference between having and imparting, between giving and receiving. Whatever He does He does with the power of a master, whatever they do it is with confession of their own weakness, as they speak, In the name of Jesus rise and walk. (Acts 3:6.)

These therefore He chose for His disciples, whom also He named Apostles, humbly born without honour, without learning, that whatever they should do that was great, it was He that should be in them and should do it. He had among them one that was evil, whom He should use in the accomplishment of His Passion, and who should be an example to His Church of suffering evil men.

The Evangelist had related above that the Lord exhorted His disciples to pray the Lord of the harvest to send labourers into His vineyard; and He now seems to be fulfilling what He had exhorted them to. For the number twelve is a perfect number, being made up of the number six, which has perfection because it is formed of its own parts, one, two, three, multiplied into one another; and the number six when doubled amounts to twelve. Wherein is openly showed that the multitude were troubled not with one single kind of affliction, but with many, and this was His pity for the multitude, to give His disciples power to heal and cleanse them.

For the number twelve, which is made up of three into four, denotes that through the four quarters of the world they were to preach the faith of the holy Trinity.