(CNN) Baba Ram Dass, psychedelic research pioneer, best-selling author and New Age guru who extolled the virtues of mindfulness and grace, has died. He was 88.

Born Richard Alpert, the future spiritual teacher met experimental psychologist Timothy Leary while the two taught at Harvard University. They founded the Harvard Psilocybin Project and shared psychedelic drugs with volunteer graduate students to explore their mind-altering effects.

The unorthodox pair were fired from Harvard in 1963 after faculty found out Alpert shared the drugs with undergraduates. They became "counter-culture icons" in their dismissal, per the Ram Dass website , taking more drugs to learn how psychedelics expanded their consciousness.

But he didn't become Ram Dass until a fateful trip to India in 1967. There he met Neem Karoli Baba, his guru, who gave Alpert the name Baba (or "father") Ram Dass, which means "servant of God," per Dass's website.

The spiritual enlightenment he experienced there prompted him in 1971 to write "Be Here Now," a best-seller his website describes as a "Western articulation of Eastern philosophy." The book became a New Age treatise on mindfulness and positivity.

He never feared death

A severe stroke in 1997 left Dass unable to speak or move part of his body. He relearned to speak and continued to teach online and host retreats from Maui, Hawaii.

"The stroke itself was not grace, but my reaction to the stroke was grace," he told the National Institute for the Clinical Application of Behavioral Medicine . "I was positive from it, I was fascinated by it. And it was changing my philosophy on life."

In September, Dass told the New York Times Magazine he'd accepted his death.

"Soul doesn't have a fear of dying," he said. "Ego has very pronounced fear of dying. The ego, this incarnation, is life and dying. The soul is infinite."

He died at home in Maui, surrounded by loved ones, according to his Instagram. The post didn't list a cause of death.

Ram Dass' fans mourn his death

Supporters mourned his death on Twitter.

"'Be Here Now' shifted my world when I was young, as it did for millions of others," Democratic presidential candidate Marianne Williamson tweeted . "Praise & thanks to a huge & radiant soul. May he be forever blessed."

Buddhist teacher Joan Halifax shared images of Dass, whom she called her close friend, during their final visit.

"The last time I saw him, sensing it might be so," she wrote. "Loving awareness...our Ram Dass."