De Plantatione

On this account also, Moses said that in the fourth year all the fruit of the tree shall be holy; for this number has an even, and an entire, and a full, and (as one may almost say) every possible reason in it, because the number ten, of which four is the parent, is the first starting place of all the numbers when put together after the unit; and the number four and the number ten are both also called "all," but the number ten is so called by reason of its operation, this number four with reference to its potentiality.