Among the things then which are perceptible only by intellect, the number seven is proved to be the only thing free from motion and accident; but among things perceptible by the external senses, it displays a great and comprehensive power, contributing to the improvement of all terrestrial things, and affecting even the periodical changes of the moon. And in what manner it does this, we must consider. The number seven when compounded of numbers beginning with the unit, makes eight-and-twenty, a perfect number, and one equalised in its parts. And the number so produced, is calculated to reproduce the revolutions of the moon, bringing her back to the point from which she first began to increase in a manner perceptible by the external senses, and to which she returns by waning. For she increases from her first crescent-shaped figure, to that of a half circle in seven days; and in seven more, she becomes a full orb; and then again she turns back, retracing the same path, like a runner of the diaulos, This refers to the Greek games. The straight race was called στάδιον or δρόμος . In the δίαυλος δρόμος the runners turned round the goal, and came back to the starting place. —Smith in v. Stadium. receding from an orb full of light, to a half circle again in seven days, and lastly, in an equal number she diminishes from a half circle to the form of a crescent; and thus the number before mentioned is completed. And the number seven by those persons who are in the habit of employing names with strict propriety is called the perfecting number; because by it, everything is perfected. And any one may receive a confirmation of this from the fact, that every organic body has three dimensions, length, depth, and breadth; and four boundaries, the point, the line, the superficies, and the solid; and by these, when combined, the number seven is made up. But it would be impossible for bodies to be measured by the number seven, according to the combination of the three dimensions, and the four boundaries, if it did not happen that the ideas of the first numbers, one, two, three and four, in in which the number ten is founded, comprised the nature of the number seven. For the aforesaid numbers have four boundaries, the first, the second, the third, the fourth, and three intervals. The first interval being that between one and two; the second, that between two and three; the third, that between three and four.
 And besides what has been already said, the growth of men from infancy to old age, when measured by the number seven, displays in a most evident manner its perfecting power; for in the first period of seven years, the putting forth of the teeth takes place. And at the end of the second period of the same length, he arrives at the age of puberty: at the end of the third period, the growth of the beard takes place. The fourth period sees him arrive at the fullness of his manly strength. The fifth seven years is the season for marriage. In the sixth period he arrives at the maturity of his understanding. The seventh period is that of the most rapid improvement and growth of both his intellectual and reasoning powers. The eighth is the sum of the perfection of both. In the ninth, his passions assume a mildness and gentleness, from being to a great degree tamed. In the tenth, the desirable end of life comes upon him, while his limbs and organic senses are still unimpaired: for excessive old age is apt to weaken and enfeeble them all.
 And Solon, the Athenian lawgiver, described these different ages in the following elegiac verses:—
 In seven years from th’ earliest breath, The child puts forth his hedge of teeth; When strengthened by a similar span, He first displays some signs of man. As in a third, his limbs increase, A beard buds o’er his changing face. When he has passed a fourth such time, His strength and vigour’s in its prime. When five times seven years o’er his head Have passed, the man should think to wed; At forty two, the wisdom’s clear To shun vile deeds of folly or fear: While seven times seven years to sense Add ready wit and eloquence. And seven years further skill admit To raise them to their perfect height. When nine such periods have passed, His powers, though milder grown, still last; When God has granted ten times seven, The aged man prepares for heaven. 
 Solon therefore thus computes the life of man by the aforesaid ten periods of seven years. But Hippocrates the physician says that there are seven It is hardly necessary to remind the reader of the description of the seven ages of man in Shakespeare. As You Like It, Act 11. sc. 7. ages of man, infancy, childhood, boyhood, youth, manhood, middle age, old age; and that these too, are measured by periods of seven, though not in the same order. And he speaks thus; In the nature of man there are seven seasons, which men call ages; infancy, childhood, boyhood, and the rest. He is an infant till he reaches his seventh year, the age of the shedding of his teeth. He is a child till he arrives at the age of puberty, which takes place in fourteen years. He is a boy till his beard begins to grow, and that time is the end of a third period of seven years. He is a youth till the completion of the growth of his whole body, which coincides with the fourth seven years. Then he is a man till he reaches his forty-ninth year, or seven times seven periods. He is a middle aged man till he is fifty-six, or eight times seven years old; and after that he is an old man.