  A fascinating use of algebra was introduced in 1814 by François-Joseph Servois (1776–1847) when he tackled differential equations by separating the differential operator  from the subject, as described in an example given above. This application of algebra captured the interest of Gregory who published a number of papers on the method of the separation of symbols, that is, the separation into operators and objects, in the CMJ. He also wrote on the foundation of algebra, and it was Gregory’s foundation that Boole embraced almost verbatim prior to writing LT. Gregory had abandoned Peacock’s principle of the permanence of equivalent forms in favor of three simple laws, one of which Boole regarded as merely a notation convention. Unfortunately these laws fell far short of what is required to justify even some of the most elementary results in algebra, like those involving subtraction. 