I recently attended the Blockchain Economy World Tour in Sydney where Dr W.Scott Stornetta presented his 'aha' moment in developing digital timestamping, one of the core components of bitcoin. It is important to acknowledge that one of the core elements that make up blockchain actually came from a hybrid solution for digital time stamping of documents - decentralized hash verification.
For those of you not familiar with digital time stamping, it was developed back in 1991 by Stuart Haber and W.Scott Stornetta, who is the Chief Scientist for First Digital Capital. Their work on digital time stamping was referenced three times in Satoshi Nakamoto's white paper on Bitcoin. In Scott's presentation he referred to his 'aha' moment as "letting the world become your witness". He went on to explain that if you are not sure who to trust in a centralized controlled environment then the best protection would be to invite the public at large to verify that this transaction took place.
This decentralized public verification and timestamping of a generated hash is one of the core components of bitcoin and blockchain. Another key observation regarding Dr. Stornetta's work is that public verification was used to publicly verify a hash that was generated on a private network. It was 1991, and his work pre-dated the development of blockchain.
Satoshi Nakamoto incorporated decentralized public verification into a decentralized currency, bitcoin. Subsequently, most of the blockchains that have followed bitcoin have also focused on building atop of a public blockchain.