The Immortality of the Soul
Fr Peter Bristow
In the famous passage from As You Like It, Shakespeare seems to be harping on the meaninglessness and futility of human existence if it is limited to the seven ages of man. His references to the "mewling and puking" infant, the whining schoolboy "creeping like snail unwillingly to school," and the soldier "full of strange oaths," are not very complimentary to this present life. And the last age seems to confirm this view:
The Whole Man
The trouble with materialism is that it tends to lead people to see man only in material terms, thus neglecting his transcendence over the world and his immortality. There is a good deal of agnosticism about eternal life in the contemporary world. One hears people comment, for example, that, at best, they are prepared to be surprised by a future life. It is based on a misunderstanding of what man is, a radical impoverishment of his true nature.
The Biblical Tradition
Central to the question is the nature of the soul. It may be defined as the life principle of a creature, that which gives it self-movement and growth, but while an animal has a corporeal soul, man's is spiritual. The Book of Genesis makes this clear in its description of man's creation: "the Lord God formed man of dust from the ground, and breathed into his nostrils the breath of life; and man became a living being."  In the first account of creation in the previous chapter we read: "Then God said, 'Let us make man in our image, after our likeness'.' Man is thus a spiritual and material being at the same time, different from the animals and other material objects, as the continuation of the account makes clear, since man alone is capable of knowing, then naming them and recognizing that he was different from them.
Using terminology derived from Aristotle and elaborated by St Thomas Aquinas, the Council of Vienne in 1312 had already called the soul "the substantial form of the body."  The "form" here does not refer to the shape, precisely because it is spiritual, but rather refers to that which gives identity to the person as well as life and movement. This principle cannot be material since the matter of the body changes completely every few years and hence the person would have no continuing identity, so it must be immaterial. In the case of the person, the soul is intrinsically independent of matter (in animals it is not) and hence what we call spiritual. In other words, it is capable of actions, such as self-reflexion, which would not be possible to a material organ. Being spiritual the soul is not made of parts and therefore cannot corrupt. This bears out the statement of the Bible that "man was made for incorruptibility." 
In the Constitution on the Church in the World, Vatican II put it this way:
How We Know
It is worthy of note here how we have derived information about such an unobservable principle as the soul, namely by its actions. This is an application of the old philosophical adage: agere sequitur esse ("action follows being") and therefore by observing the actions we can deduce back to the being of things. Some of man's actions can only flow from a spiritual principle, as, for example, his use of language and his power of self-consciousness. Man's linguistic ability indicates the degree of his knowledge. He is able not only to know individual things by sensation as do animals, but he knows what kind of things they are (essences) and is able to give them common names (universals). Furthermore, he is able to know other "universals" such as good and evil, and to make choices. As the Book of Sirach tells us: "He made for them tongue and eyes; he gave them ears and a mind for thinking. He filled them with knowledge and understanding and showed them good and evil."
Drawbacks of Dualism
Man is thus "an individual substance of rational nature" characterized by the two principal faculties of the soul, namely intellect and will, which nevertheless work through the material organs of the senses. This carefully balanced unity of man has always been threatened by the dualism of the Platonic and Cartesian schools. The drawbacks of this position are considerable and dangerous. To say, as Descartes does, that man is two substances of body and soul, is to make a satisfactory connection between them impossible.
Such a position has been held up to ridicule, notably by Gilbert Ryle, who describes the dualistic concept of man as "the ghost in the machine." To characterize the soul as a ghost is to play into the hands of materialists who can properly say: if we cannot know the soul, then what use have we for it?
The glorified body will be so dominated by the soul after the final resurrection, that it too by that time will be immune from corruption. The mortality of man's body, "sans teeth, sans eyes, sans taste, sans everything," will be clothed in immortality. The "mere oblivion" to which he is apparently consigned finds its explanation in eternal life.
2. Wisdom 3,1-2;
3. John 3,16;
4. 1 Cor. 15,53;
5. Gen. 2,7;
7. Gen. 2, 18-20;
8. e.g. Ps. 144,21 and Is. 66,23;
9. Matt. 10,28;
10. Fifth Lateran Council, 1518, Dz. 1440 or 738;
11. Pius XII, Humani Generis, 1950, Dz. 3896;
12. Council of Vienne, 1312, Dz. 902;
13. Wisdom 2,23;
14. Gaudium et Spes no. 14
15. Sirach 17,5-6;
16. Gaudium et Spes no. 15.
Copyright ©; Fr Peter Bristow 2000
This version: 26th December 2004