<p><span class="h-card" translate="no"><a href="https://mastodon.social/@whitequark" class="u-url mention">@<span>whitequark</span></a></span> i don't know anything about this stuff but this question really got in my head so i had to go looking for the answer and i think we might have to blame Leibniz?</p><p>looks like 'variable' and 'value' in this sense were used together in Historia et Origo Calculi Differentialis some time between 1714 and 1716, though maybe before as well.</p><p><a href="https://archive.org/details/historiaetorigo00gerhgoog/page/n34/mode/2up" target="_blank" rel="nofollow noopener noreferrer" translate="no"><span class="invisible">https://</span><span class="ellipsis">archive.org/details/historiaet</span><span class="invisible">origo00gerhgoog/page/n34/mode/2up</span></a></p><p><a href="https://www.jstor.org/stable/pdf/27900612.pdf" target="_blank" rel="nofollow noopener noreferrer" translate="no"><span class="invisible">https://www.</span><span class="ellipsis">jstor.org/stable/pdf/27900612.</span><span class="invisible">pdf</span></a></p>
