Plotinus, when younger, heard of the yoga systems and wanted to travel to India to investigate them. He was unable to do so and, when older, was unimpelled to do so any longer. He criticized one of the principal claims of hatha yoga as well as of mantra yoga when he asked sceptically how "specially directed breathings and certain sounds, to which is ascribed magic potency upon the Supreme, could act upon the unembodied Spirit." What he himself taught was very close to gnana yoga, although it originated with the Neoplatonic doctrine of Ammonius in Alexandria.
-- Notebooks Category 15: The Orient > Chapter 7: Related Entries > # 31