Philo Judaeus De Opificio Mundi 106

[106] And it is also affirmed for the particular praise of the number seven, that it has a very admirable rank in nature, because it is composed of three and four. And if any one doubles the the third number after the unit, he will find a square; and if he doubles the fourth number, he will find a cube. And if he doubles the seventh from both, he will both a cube and a square; therefore, the third number from the unit is a square in a double ratio. And the fourth number, eight, is a cube. And the seventh number, being sixty-four, is both a cube and a square at the same time; so that the seventh number is really a perfecting one, signifying both equalities, —the plane superficies by the square, according to the connection with the number three, and the solid by the cube according to its relationship to the number four; and of the numbers three and four, are composed the number seven.