Just as a counterpoint, in the book &quot;Moonwalking with Einstein&quot;, the author talks quite a bit about the fact that many of these methods survived for a long long time, and people in the past considered memory an incredibly important proof of someone being educated.<p>The methods seem to have been &quot;lost&quot; mostly when better options for external memory (e.g. writing and printing) became more universal. (iirc - i&#x27;m probably messing this up somewhat).