Bip39 Mnemonic Algorithm. From this point ahead the seed could be published on paper or spoken around telephone and this opened up new, Actual physical means of backing up the seed (several paper copies in numerous spots, strong copies on metallic plates with added protection from hearth/flood and so on.). https://classifylist.com/story20362349/bip39-word-list-bitcoin-bip39-standalone-can-be-fun-for-anyone