3. Firstly; with respect to the first, then, it is to be noted that there be two kinds of unction: an _external_, which is material or corporeal, and visible; and an _internal_, which is spiritual and invisible. The body is anointed visibly with the external unction; the heart invisibly by the internal. Of the first, the Apostle S. James saith, 'Is any sick among you? Let him call for the elders of the Church; and let them pray over him, anointing him with oil in the name of the Lord; and the prayer of faith shall save the sick.' [Footnote 490] Of the second the Apostle S. John saith, 'But the anointing which ye have received of Him abideth in you, and ye need not that any man teach you: but the same anointing teacheth you of all things.' [Footnote 491] The external unction is a sign of the internal. But the internal is not only a sign, that is a thing signified, but a sacrament also; because if it be worthily received, it either effecteth, or without doubt increaseth, that which it doth signify--for instance, healing: according to the saying, 'They shall lay their hands upon the sick, and they shall be healed.' [Footnote 492] [Footnote 490: S. James v, 14.] [Footnote 491: I S. John ii, 27.] [Footnote 492: See Acts xxviii, 8.] Secondly; with respect to the second point, you must know that in making use of the external and visible unction, two sorts of oil are consecrated: namely, holy oil, or the oil of the catechumens, with which catechumens are anointed; and the oil of the sick, with which the sick are anointed. Of which kind of unction the authority of S. James quoted above doth speak, 'Is any sick among you,' etc. {135} But in what way the benediction of these two sorts of oil and of chrism is performed will be declared in the sixth book in the chapter upon the Fifth Day of the Holy Week. [Footnote 493] [Footnote 493: It has not been thought necessary to translate the passages referred to.] 4. But is it asked why the sick and the catechumens are anointed with oil? I answer, in order that the invisible benefits may be more easily received through the visible signs: for as oil by expelling weakness refresheth the wearied limbs, and as it from its own natural qualities affordeth light, so it is to be believed that unction with consecrated oil, the which is a type of faith expelling sin, doth impart health to the soul and doth afford it light. Herein the visible oil is in the outward sign, the invisible oil in the inward sacrament; and the spiritual oil is within. For the oil of the sick we have received authority from the apostles; for the oil of the catechumens from apostolical men.