XXVII. (113) And again Moses says, “Its fruit shall be impure for three days, it shall not be Eaten;”{25}{#le 19:23.} as if in fact it were customary for it to be purified for ever. We must, therefore, say that this is one of those expressions which have a concealed meaning, since the words themselves are not quite consistent with it; for the expression is an ambiguous one; for it bears one sense of this kind, the fruit shall remain for three years; and then there is a distinct injunction, “it shall not be eaten before it is purified.” But there is also another meaning, “the fruit of the tree shall for three years be unpurified, and while in that state it shall not be eaten.” (114) According, then, to the former statement one may understand it in this manner: the three years being taken from time which is divided into three portions; for it is the nature of time to be divided into the past, the present, and the future; therefore the fruit of education will exist, and will endure, and will last unimpaired through all the divisions of time, a statement equivalent toùit will never receive any corruption, for the nature of good is imperishable. But the fruit which is not purified shall not be eaten; inasmuch as virtuous reasons, duly purified and rendered sound, nourish the soul, and give vigour to the mind; but the opposite kinds are not nutritious, but bring disease and destruction on the soul. (115) According to the other meaning, as in the disputes of dialecticians, the word “undemonstrated” is used in a double sense, either of a proposition which it is hard to demonstrate by reason of its difficulty, or of one which is intrinsically so plain as to require no demonstration, and the truth of which is established not by the testimony of any one else, but by its own internal evidence. So also fruit may be understood as not being purified, either when it is so impure as to be difficulty to purify, or when it requires no purification, but is bright, and clear, and pure of itself. (116) Such now is the fruit of education; being for three years, that is to say for all time, divided as it is into three portions, most completely pure and brilliant, being overshadowed by no injurious thing, and having no need whatever of any washings or purifications, or any thing else whatever which tends to cleansing.

XXVIII. (117) “But in the fourth year,” says the scripture, “all the fruit of the tree shall be sacred, being praised by the Lord.”{26}{#le 19:25.} The prophetic books appear often to dignify the number four in many places of the exposition of the law, and most especially in the account of the creation of the universe; (118) for the light which is perceptible by the outward senses, and held in honour, being that which throws the most brilliant light both upon itself and upon other things, and upon its own parents the sun and the moon, and upon the most sacred company of the stars, which by their rising and setting fix the boundaries of night and day, and moreover, of months and years, and which have shown the nature of number, to which, also, the greatest good of the soul is attributed, Moses says was created on the fourth day. (119) And now he honours this day in a remarkable degree, assigning the fruit of the trees to God, in accordance with no other time than with the fourth year after they are planted; (120) for this has a principle in it very consistent with nature and with good morals. At all events it so happens that the roots of the universe, the elements of which the world is composed, are fourùearth, water, air, and fire. Also, that the seasons of the year are equal in number, namely, winter and summer, and those others which are between these two, spring and autumn. (121) And as this is the most ancient of all square numbers, it is found to exist in right angles, as the figure of a square in geometry shows. And right angles are manifest examples of correctness of reason. And right reason is an everlasting fountain of virtues. (122) It follows, therefore, of necessity that the sides of a square must be all equal to one another. And equality is the parent of justice, which is the mistress and ruler of all the virtues, so that it is not proved that this number four is the symbol of equality, and justice, and of all virtue, beyond any other number. (123) And the number four is likewise called “all,” because it comprehends in its power the numbers up to ten, and the number ten itself.