During Adi Shankara’s time, Hinduism was in peril, almost on death bed with many factions, many of the scriptures almost getting lost, with not many followers. He single handedly unified various factions under one umbrella, going around India multiple times defeating different philosophies and establishing structure to ensure that the situation does not happen again.
Additionally, he ensured that there is enough mandatory interconnect between various geographies of India, so that they again don’t form silos. For ex: Sureshwaracharya, who hailed from the north was placed in charge of the mutt in the south, while Totaka form the south was sent to Badri in the north. Badrinath temple is mandated to have Namboodari (from Kerala) priests, while Pashupatinath needs to have priests from Karnataka. Kashi Vishwanath is made to have Nepali priests, and Rameshwarm is mandated to have Maharashtrian priests.
Apart from these structural reforms, he also revived and commented on all the major Hindu scriptures, including Upanishads, Bhagavad Gita and Bramha-Sutras. His work become the basis for every other philosopher that came later, including Madhvacharya, Ramanujacharya and many others.
As if all this was not enough, wrote texts like Vivekachudamani, and strotras like aatma-shatakam, Bhaja-Govindam, which inspires and guide many of us.
This way, work started by 9th incarnation, Gautam Buddha, of moving people away from karma-kanda, was completed by Adi Shankara. He not only completed it, but set up systems in such a way that, even after a millennia, vedanta is firmly rooted and going strong.
As per all major estimates, he lived from 788-820 CE and what is achieved in those 32 years is beyond what many of us can do in thousands of lifetimes. On his birth anniversary, lets take a moment to thank this son of Kalady (today’s Kerala), and reflect on what we can do, if not for others at least for ourselves, to grow on the spiritual path.
If you have time, please do watch a movie made on him in Sanskrit, in 1983: https://www.youtube.com/watch?v=aZUxmcCT4YI
This movie doesn’t have today’s polished cinematography, but due to absence of drama, conveys meaning better, also was the first movie made in Sanskrit.