Swami Vivekandanda on Adi Shankaryacharya
"The greatest teacher of the Vedanta philosophy was Shankaracharya. By solid reasoning he extracted from the Vedas the truths of Vedanta, and on them built up the wonderful system of Jnana that is taught in his commentaries" 1/6
Swami Vivekananda considered Adi Shankaracharya (Adi Shankara) as the greatest teacher of Vedanta philosophy.
Vivekananda was an admirer of Adi Shankara and translated Adi Shankara’s poem Atma Shatakam (also known as Nirvana Shatakam).
Shankara came, and showed that the real essence of Buddhism and that of the Vedanta are not very different, but that the disciples did not understand the Master and have degraded themselves, denied the existence of the soul and of God, and have become atheists.
Vivekananda said "Shankaracharya had caught the rhythm of the Vedas, the national cadence. Indeed I always imagine that he had some vision such as mine when he was young, and recovered the ancient music that way..."
Shankara taught that 3 things were the great gifts of God: Human Body, Thirst after God & a Teacher who can show up the light. When these three great gifts are ours, we may know that our redemption is at hand. Only knowledge can free and save us but with knowledge must go virtue.