Chinese Zen master Guo Jun said that the beginner’s mind is like a vessel that is dirty. No matter what we pour into this dirty vessel; no matter how nutritious it is, it becomes contaminated. Zen Buddhism, and with that, Buddhism, in general, cannot be poured into a mind filled with prejudices, especially, prejudices which run contrary to the discourses of the Buddha.
In a word, the beginner’s mind is a closed mind. What ever they seem to have learned about Zen Buddhism is wrong. Sometimes their attitude is like an inverted vessel which doesn’t want to receive anything; sometimes they are like a vessel overfull so that it can’t receive anything. The mind of a beginner is also like a vessel with cracks in it. Anything of value that is poured into it is not retained.
From the standpoint of Chinese Zen, the beginner’s mind is like a raw recruit’s first arrival at MCRD (Marine Corps Recruit Depot). The recruit is not yet a Marine. He lacks the proper Marine Corps attitude. He has to drop his former attitudes—all of them—and fully adopt the Marine Corps attitude. What Shunryu Suzuki says in his book, Zen Mind, Beginner‘s Mind, runs contrary to Chinese Zen and the required attitude of a Zen beginner.
“In Japan we have the phrase shoshin, which means "beginner's mind." The goal of practice is always to keep our beginner's mind. Suppose you recite the Prajna Paramita Sutra only once. It might be a very good recitation. But what would happen to you if you recited it twice, three times, four times, or more? You might easily lose your original attitude towards it. The same thing will happen in your other Zen practices. For a while you will keep your beginner's mind, but if you continue to practice one, two, three years or more, although you may improve some, you are liable to lose the limitless meaning of original mind.”
Suzuki seems to not remember his own days as a Zen beginner; who couldn’t tell shit from Shinola; who was clueless as to the actual goal of Zen which is to realize our true nature. When he says nonsense like, “In the beginner's mind there are many possibilities; in the expert's mind there are few,” he is really saying the beginner’s mind is the monkey mind while the expert’s mind is disciplined and understands that Zen demands that we see our true nature—it’s a life and death matter. This is what the expert is seeking with every fiber of his or her being. Nothing else. Unlike the beginner's mind, the expert’s mind is not distracted by infinite possibilities and deceptions.