It may be asked, how a number, hitherto almost entirely overlooked as a base of numeration, is suddenly found to be so well suited to the purpose. The fact is, the present base being accepted as proper for numeration, however erroneously, it is assumed to be proper for gradation also; and a very flattering assumption it is, promising a perfectly homogeneous system of weights, measures, coins, and numbers, than which nothing can be more desirable; but, siren-like, it draws the mind away from a proper investigation of the subject, and the basic qualities of numbers, being unquestioned, remain unknown. When the natural order is adopted, and the base of gradation is ascertained by its adaptation to things, and the base of numeration by its agreement with that of gradation, then, the basic qualities of numbers being questioned, two is found to be proper to the first use, and eight to the second. The idea of changing the base of numeration will appear to most persons as absurd, and its realization as impossible; yet the probability is, it will be done. The question is one of time rather than of fact, and there is plenty of time. The diffusion of education will ultimately cause it to be demanded. A change of notation is not an impossible thing. The Greeks changed theirs, first for the alphabetic, and afterwards, with the rest of the civilized world, for the Arabic,--both greater changes than that now proposed. A change of numeration is truly a more serious matter, yet the difficulty may not be as great as our apprehensions paint it. Its inauguration must not be compared with that of French gradation, which, though theoretically perfect, is practically absurd.