More than 2,500 years ago, a man decided to find out why there is suffering, and how to overcome it. He succeeded, and became known as "The Buddha," which means, "One who is awake." Since then, there have emerged many variations and interpretations of what he taught, with some believing that his teachings were something he invented or created on his own. Contrary to this belief, he said,
"I have seen an ancient path, an ancient road traversed by the rightly enlightened ones of former times. And what is that ancient path, that ancient road? It is just this noble eight-fold path." - Buddha Shakyamuni, Samyutta Nikaya ii.106
Therefore, his knowledge — what in Greek is called Gnosis — existed before he did, and he only taught what he understood of that ancient knowledge.