The late Dr Darwin's family seem dissatisfied with my impartiality. I see they wanted to have had only the lights in his character shewn, and all its shades omitted. On the contrary, several of my friends murmur that I have not... sufficiently stigmatized his irreligion; at least his long insinuated contempt of revelation, and of what appeared to him the improbability of the mediatorial sacrifice. Others are chagrined that my father's satirically-playful epigram found no place in the [https://archive.org/details/memoirsoflifeofd00sewa/page/n6/mode/1up?view=theater memoirs of Dr Darwin.] You have probably seen it. Its subject was the motto he inscribed on his family-arms, which are three scollop-shells. Omnía e conchis [All from shells], allusive to his favourite hypothesis. On his , in the year 1770, he painted the arms thus inscribed. Soon after my father wrote and sent him the epigram. ...[Erasmus Darwin] painted his chaise afresh, omitted the arms and their motto, and substituted his cypher. Though my father never published the lines, the sin of having written them was never forgiven by him ...Friends til that hour, Dr Darwin never afterwards mentioned my father with respect.As to the Memoirs, neither party, whose complaints are so opposite, have taught me to repent that I endeavoured to poise the agitated scales of characteristic opinion and of criticism, with an even hand, while I respected the feelings of Dr R. Darwin too much to lash with acrimony that unfortunate and fastidious proneness to scepticism, which iced his affections, and bewildered his great and noble understanding, in the blind mazes of metaphysic conjecture.
source
Letters of Anna Seward: written between the years 1784 and 1807 (1811) [https://archive.org/details/lettersannasewa07consgoog/page/n154/mode/1up Vol. 6, Letter XXIII. Lieut. Col. R. Wolseley. Lichfield, March 21, 1804.] pp. 136-137. Note: Omnía e conchis