XXX. (101) If therefore we call the invisible soul the terrestrial habitation of the invisible God, we shall be speaking justly and according to reason; but that the house may be firm and beautiful, let a good disposition and knowledge be laid as its foundations, and on these foundations let the virtues be built up in union with good actions, and let the ornaments of the front be the due comprehension of the encyclical branches of elementary instruction; (102) for from goodness of disposition arise skill, perseverance, memory; and from knowledge arise learning and attention, as the roots of a tree which is about to bring forth eatable fruit, and without which it is impossible to bring the intellect to perfection. (103) But by the virtues, and by actions in accordance with them, a firm and strong foundation for a lasting building is secured, in order that anything which may endeavour to separate and alienate the soul from honesty and make it such another haunt, may be powerless against so strong a defence, (104) and by means of the study of the encyclical branches of elementary education, the things requisite for the ornament of the soul are provided; for as whitewashing, and paintings, and tablets, and the arrangement of costly stones, by which men decorate not merely the walls, but even the lower parts of their houses, and all other such things as these do not contribute to strength, but only give pleasure to those who live in the house; (105) so the knowledge of the encyclical accomplishments decorates the whole habitation of the soul, while grammar investigates the principles of poetry and follows up the history of ancient events, and geometry labours at equalities according to analogy, and endeavours to remedy whatever in us is deficient in rhythm or in moderation, or in harmony, by giving us rhythm, and moderation, and harmony, by means of a polished system of music; and rhetoric aims at giving us acuteness in everything, and at properly adapting all proper interpretations to everything, claiming for itself the control of all intenseness and all the vehement affections, and again of all relaxations and pleasures, with great freedom of speech, and a successful application of the organs of language and voice.