Since the apostle commands the Mystery of Holy Unction to be performed for healing from illness, it is clear that it should not be performed only over the sick who are very near death and offer no hope of recovery.
On the contrary, according to the exact meaning of the original text, this mystery should be performed over the sick who may have strength to call the presbyters of the Church.
The apostle does not indicate the number of presbyters. "But custom has handed down," says Symeon of Thessalonica, "that seven be called, corresponding to the sevenfold number of the Gifts of the Spirit listed by the prophet Isaiah.
Others call three, for the power of the Trinity. In case of necessity, even fewer than three may be called. Yet everything must be pronounced that has been handed down to be pronounced."
Even the apostles anointed many sick people with oil and healed them. See Mk 6:13.
This is why the Apostle James speaks of the Mystery of Holy Unction as something known and as concerning all places and times.
Besides prayer and anointing with oil, there is also the laying on of hands. Jesus Christ spoke of this to the apostles, and through them to their successors: "They will lay hands on the sick, and they will recover" (Mk 16:18).
Thus one must think that this mystery was established by Jesus Christ Himself.
For the performance of the mystery to be effective, the apostle requires prayer filled with living faith, both from the one performing the mystery and from the one over whom it is performed.
By mentioning presbyters, he shows that the Christians of the dispersion then formed separate church communities governed by several presbyters.
As pastors of the Church, these presbyters possessed, by succession from the apostles, the right to forgive sins. See Jn 20:23.