Although Ryogen was not a direct disciple of Saicho (Dengyo Daishi) and his rank was not high, he gradually distinguished himself as an able priest through refuting high priests of traditional Buddhist temples in Nanto (southern capital (Nara)) or praying safe delivery of a child for the Empress of Emperor Murakami, and finally he achieved Tendai-zasu, the supreme position in the Tendai Sect, in 966.
良源は、最澄（伝教大師）の直系の弟子ではなく、身分も高くはなかったが、南都（奈良）の旧仏教寺院の高僧と法論を行って論破したり、村上天皇の皇后の安産祈願を行うなどして徐々に頭角を現わし、康保3年（966年）には天台宗最高の地位である天台座主に上り詰めた。