[Footnote i-104: In 1750 he wrote: "Nor is it of much importance to us, to know the manner in which nature executes her laws; 'tis enough if we know the laws themselves. 'Tis of real use to know that china left in the air unsupported will fall and break; but _how_ it comes to fall, and _why_ it breaks, are matters of speculation. 'Tis a pleasure indeed to know them, but we can preserve our china without it" (_Writings_, II, 434-5). We remember that even Sir Isaac Newton confessed that "the _cause_ of gravity is what I do not pretend to know" (_Works of Richard Bentley_, London, 1838, III, 210). He observed that "Gravity must be caused by an agent acting constantly according to certain laws; but whether this agent be material or immaterial, I have left to the consideration of my readers" (_ibid._, 212).] [Footnote i-105: _Pennsylvania Magazine of History and Biography_, XIII, 247-8 (1889).] [Footnote i-106: Franklin was unable to prevail upon Johnson to accept the provostship of the Academy. In 1752 he printed Johnson's _Elementa Philosophica_ and suggested in _Idea of the English School_ that it be used in the Academy. In a letter of 1754 Franklin informs Johnson that the grammatical and mathematical parts were already being used--the rest would be when the instructors and pupils were ready for it (E. E. Beardsley, _Life and Correspondence of S. Johnson, D. D._, 2d ed., New York, 1874, 180-1). In the _Elementa Philosophica_ Johnson stresses the use of mathematics in man's study of nature (p. xv). Through mathematics, an indispensable aid in "considering that wonderful and amazing Power, that All-comprehending Wisdom, that inimitable Beauty, that surprizing Harmony, that immutable Order, which abundantly discover themselves in the Formation and Government of the Universe, we are led to their divine Original, who is the unexhausted Source, the glorious Fountain of all Perfection ..." (_ibid._, xiii). The _Elementa_ is a rhapsodic manual extolling the discovery of the Deity in his Work, through the study of the physical laws of the creation. Although subordinated to this, there are frequent reactions against Lockian sensationalism, suggesting an ecstatic mystical union between man and God. On the whole, the volume is a treatise on the glories of a natural religion (a religion of course which buttresses rather than refutes scriptural religion).]