https://www.etymonline.com/search?q=congeries wrote:
congeries (n.) "a collection into one mass or aggregate," 1610s, from Latin congeries "heap, pile, collected mass," from congerere "to bring together, pile up," from assimilated form of com "with, together" (see con-) + gerere "to carry, perform" (see gest). False singular congery is attested by 1866.
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gest (n.) "famous deed, exploit," more commonly "story of great deeds, tale of adventure," c. 1300, from Old French geste, jeste "action, exploit, romance, history" (of celebrated people or actions), from Medieval Latin gesta "actions, exploits, deeds, achievements," noun use of neuter plural of Latin gestus, past participle of gerere "to carry on, wage, perform," which de Vaan says is considered to be from the same root as agere "to set in motion, drive forward, do, perform". Now only as a deliberate archaism. Jest (n.) is the same word, with a decayed sense.
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jest (n.) early 13c., geste, "narrative of exploits," from Old French geste "action, exploit," from Latin gesta "deeds," neuter plural of gestus, past participle of gerere "to carry, behave, act, perform" (see gest, which preserves the original sense). Sense descended through "idle tale" (late 15c.) to "mocking speech, raillery" (1540s) to "joke" (1550s). Also "a laughing-stock" (1590s).