Interesting! Kashmir Shaivism teaches the exact same meditation recorded in texts from the period 975–1025 CE. You intone a mantra 108 times and visualize the mantra beaming with an immortal elixir that drips down from the Crown, in a similar way clearing all illnesses, not only of the body but also the spirit. There are some very similar meditations in Daoism as well from our Maoshan school of sorcery. Historically, this Zen sect was not Buddhist (its martial origins are commonly acknowledged) as its founder traveled to China where he probably picked this up from the Daoists! Interesting nevertheless!