Question: What is the “self” D.T. Suzuki refers to?

Complete question: D.T. Suzuki: “By the aid of the Sutras and by enquiring into the doctrines he has come to understand something; he has found the traces. He now knows that things, however multitudinous, are of one substance, and that the objective world is a reflection of the self” (Essays in Zen Buddhism, The Ten Cow-Herding Steps). What is the “self” he refers to?

Answer: Suzuki was an intellectual who “came to understand something” by feeding his intellect with doctrines found in books…
Buddhas, patriarchs and monks, for their part, experience reality by themselves. They may not talk about it, but they invite us to do the same.
Ultimate reality is a whole, and this whole is one single Mind: Buddha.
All the phenomena that surge from it are impermanent and interdependent. A phenomenon, like our existence, cannot be separated from other existences; it depends on and includes all existences.
We can thus say that there is no Self, or that the whole universe is our Self. It is ungraspable with our mental mind, and can only be experienced in the practice of zazen, Buddha’s practice.
But the mental mind, grabbing hold of our sensations and our perceptions, gives us a representation, an image of who we are, which we call the “Me”.