But what we allow into our minds cannot be erased and so it's in our own best interest to be very careful what we let inside. We're our own gatekeepers, and by taking this responsibility we do not become easily offended.
While we both essentially concur with the words, it seemed clear that he and I hold two completely different interpretations.
From one perspective, "Hear no evil. See no evil. Speak no evil." Experience with evil will tend to draw the person in and corrupt the person. The only possible solution to maintain goodness and purity is to avoid evil. Don't let evil in and you will remain pure. Do not associate with evil people. Do not read material with evil content. Do not look at evil stirring images. Do not visit places where evil might occur. And so forth.
It is clear that many people do live this way. Problem solved, right? Maybe until two people or two groups disagree upon what is and what is not evil---perhaps evolving until one decides the other is evil for not sharing the definition...
But what are the more individual consequences of such a life?
The mind is a very powerful device for labeling, filtering, and selecting things, and it can obviously be trained. The mind can be trained so that, even subconsciously, every thing and every experience is labeled "evil" or "not evil." There can even be trained reactions, such as fainting on hearing foul language or averting one's eyes on seeing what is sexually suggestive. Even higher order impulses might develop, such as, "If I see evil, I must act to destroy it!"
Once all of these layers are in place, how long is it before the mind finds itself in an irresolvable dilemma? How long can it possibly be before a person finds himself on the wrong side of his own rules? How long can it possibly be before the person, with imperfect information and understanding about another's situation, mistakenly applies the label "evil" to another, causing that person harm, or even harming an innocent bystander in the process?
We construct and apply simple models to our lives---everyone does---but life is seldom so simple for long. Eventually the mind faces the fact that whatever model was in place does not fit the observations. What now? This is a point for suffering, a place where the expected does not occur or the unexpected does. So, is a better model the answer to life's problems? Is the model wherein you and your mind are distinct and it is your responsibility to fence off evil from your mind the successful model for life? How could it be?
So, what of another perspective? We have to delve deeper...
What is the gatekeeper of the mind if it is not the mind itself? Can the thoughts "This is good," and "This is evil" live outside the mind? If the mind decides to fence certain thoughts out of the mind, then are those thoughts not already inside the mind's gate?
The thought "Do not admit evil into the mind" in itself admits "evil" into the mind, and it sets into motion the discriminating process. Now you are a machine, finding evil everywhere, deciding right and wrong, dealing with it, or fencing it off, or running from it, or being corrupted by it when you embrace it...
A pure mind does not discriminate between "good" and "evil." A pure mind has no fence and has no gate---there is no need. Seeing things as they are---whether as a manifestation of God's Grace, Buddha Nature, Mother Nature, or anything else---no evil enters the mind and there is no corruption as a result.
To achieve this, it seems then that one of the first objectives of the mind's gatekeeper must ensure that thoughts of a gate or a gatekeeper do not enter the mind... Can this state be found? Think back: There was a time when you saw everything with a beginner's mind, when there was no good, no evil, no fence between them, and no gate to be watched. What happened to your original mind?
Alas, even these thoughts are flawed, but hopefully they point toward the truth.