Unfortunately that file is gone. If anyone could upload it it would be a great help.
It presents a Japanese perspective of what constitutes the Buddha's teachings. I'm not sure if it really fits for the category of introduction since it contains many different levels of teachings without explaining the connection.
"If the Buddha-Nature is seen, there will be no seeing of a nature in any thing."
(Nirvana Sutra, T12n374p521b3; tr. Yamamoto)
"Neither cultivation nor seated meditation — this is the pure Chan of Tathagata."
(Mazu Daoyi, X1321p3b23; tr. Jinhua Jia)
"With sudden enlightenment to Tathagata Chan,
The six paramitas and myriad means are complete within that essence."
(Yongjia Xuanjue, T2014p395c14; tr. from "The Sword of Wisdom")