Containing the substance of all that has been written on this subject by Theo of Smyrna, Nicomachus, Iamblichus, and Boetius. Together with some remarkable particulars respecting perfect, amicable, and other number, which are not to be found in the writings of any ancient or modern mathematicians. Likewise, a specimen of the manner in which the Pythagoreans philosophized about number; and a development of their mystical and theological arithmetic.