1706, from Latin exponentem (nominative exponens), present participle of exponere "put forth" (see expound). Earliest use is the mathematical one (said to have been introduced in algebra by Descartes) for the symbol placed above and to the right of another to indicate by what power the base number is to be raised. The sense of "one who expounds" is by 1812. As an adjective, "exemplifying, explicating," from 1580s.
"exponent of mystical theology, one who accepts or preaches some form of mysticism," 1670s, from mystic (adj.). In Middle English, the noun meant "symbolic meaning, interpretation" (early 14c.).
member of a German Anabaptist sect, 1560s, from name of Menno Simons (1492-1559), founder of the sect in Friesland and chief exponent of its doctrines (adult baptism, refusal of oaths, civic offices, and support of the state in war), + -ite (1). As an adjective by 1727. Alternative form Mennonist (n.) is attested from 1640s.
"of or in the mode of James," 1875 in reference to William James (1842-1910), U.S. philosopher and exponent of pragmatism; 1905 in reference to his brother Henry James (1843-1916), U.S. expatriate novelist.
[T]he long sentences piling themselves up in elaborate phrase after phrase, the lightning incision, the pauses, the slightly shaking admonitory gesture with its ‘wu-await a little, wait a little, something will come’; blague and benignity and the weight of so many years’ careful, incessant labour of minute observation always there to enrich the talk. I had heard it but seldom, yet it is all unforgettable. […] No man who has not lived on both sides of the Atlantic can well appraise Henry James; his death marks the end of a period. [Ezra Pound, from “Henry James,” Little Review, August 1918]
1818, on model of German clerisei, from Late Latin clericia, related to clericus (see cleric); apparently coined by Coleridge, who used it to mean "the learned men of a nation, its poets, philosophers, and scholars," "to express a notion no longer associated with CLERGY" [OED]. But since the 1840s it has since sometimes been used in the sense "the clergy," as distinguished from the laity.
The clerisy of the nation (a far apter exponent of the thing meant, than the term which the usus et norma loquendi forces on me), the clerisy, I say, or national church, in its primary acceptation and original intention comprehended the learned of all denominations;—the sages and professors of law and jurisprudence; of medicine and physiology; of music; of military and civil architec[t]ure; of the physical sciences; with the mathematical as the common organ of the preceding; in short, all the so called liberal arts and sciences, the possession and application of which constitute the civilization of a country, as well as the Theological. [Coleridge, "On the Constitution of the Church and State," 1830]