The work of the Spirit has been outlined in the Gospels. Our Lord at His Last Supper, when His teaching seems to have expounded in the full splendour and height of its tremendous mysteries, when, if ever, the Apostles could truly say that He had passed out of the realm of parable and had come into the deepest ways of truth - our Lord at His Last Supper said that His going away was necessary for the coming of the Paraclete. He had to die and rise and ascend, and then from the right hand of the Father His own work would continue in a ceaseless intercession for all the children of men. On earth, however, His place would be taken by the Holy Ghost, who should teach the Apostles all things, and bring back to their minds whatever He had taught to them. In this way was guaranteed the infallibility and growth in doctrine which are the work of the Spirit. Our Lord had certainly to temper His doctrine to the minds of His hearers. He could not from the first reveal to them the full meaning of His words. In the beginning, indeed, the need was simply for the main ideas to sink gradually in: then slowly the other less important though necessary truths could be added. The little that He did teach was not too clearly retained, so that He had frequently to be upbraiding them with not having understood His meaning. The length of His stay with them had not made them always grasp of what spirit they were. What should happen when He was gone? He answers that only His going will set them on their own strength.
As the Church grew in the range and depth of her doctrine, so must she for ever grow. The problems that distract her must increase; with each generation they change their expression, for the forms of thought are the most mobile and uncertain of all human construction. A cathedral lasts longer than a philosophy, a haunting song outlives the latest system of metaphysics. Questions are settled only that the restless mind of man may add another difficulty to the solution that allayed its previous doubt. Rapier-like in its power to find the weak joint in the armour, reason, sharpened by scientific criticism, picks here and there at the composition of the Creed. New conditions, new discoveries, new languages, require new attitudes, new difficulties, new adjustments of old principles. Obviously it is not sufficient to know the rules of the art, the great trouble and anxiety comes in their application. So, too, is it in the Faith. The articles of belief seem at times to suggest contradictory answers to the problem that happens at the moment to be perplexing our minds. According to one mystery, one solution; according to a second, another. How to choose and select, to decree without fear or favour, without danger of mistake, is the work of the Church. Not merely in the broad line of the Church, but in the individual soul, the same task must go on the balance between what has to be discarded as of passing significance and what is of abiding import. I have to discover for myself which is the mere adventitious dressing of some bygone form of thought and which is of enduring truth. Yet not indeed for myself, since in the Church abides for ever the indwelling of the Spirit of God.
Thus came the Holy Spirit on the first Whitsunday. He came, we read, in the rush of a great wind and in the form of fire, to typify the illumination of the mind by faith and the impulse given to the will by love. He came to teach all things, to recall to their minds the full doctrine of Christ. At once after their reception of His grace, the Apostles become changed men. No longer timid and frightened followers who fled at the first sight of danger and denied with an oath that they had ever known the name of Christ, they now become glad missionaries, declaring themselves willing to suffer in defence of that name. In council chambers and before kings they announce the Gospel. So, too, when perplexities come as to whether or no they should force on all Christians the ceremonies of the Old Law as being of binding value on the conscience of the New Dispensation, they assemble, discuss and decree in a phrase that clearly marks their own appreciation of the place they had to take in giving to the world the message of Christ. " It has seemed good to the Holy Spirit and to us." They and the Holy Spirit are fellow-workers in the apostolate of Christ. The revelation made to them by their Master was but a grain of mustard-seed compared with the full development that should come after. It should grow from that till it included all truth; but the knowledge of every detail of that truth would not at once be necessary, so the gradual unfolding was left to the work of the Spirit. The work, then, of the Holy Ghost is twofold: it is to inflame the love, and it is to enlighten the mind. Let me wait patiently for this illumination of my spirit by the Holy Spirit, putting no obstacle in the way, praying daily for that illumination which shall light as by a vision my view of life.
- text taken from Meditations for Layfolk by Father Bede Jarrett, O.P.