People do not simply take it into their heads to walk into some house if the owner is present. But if a house is empty, passers-by will casually come in, the lack of human presence will encourage foxes and owls to make themselves at home there, and tree spirits and suchlike bizarre creatures will even appear.
Likewise, since a mirror has no inherent shape or color, everything can appear reflected in it. If it had its own color and shape, it wouldn’t reflect other things.
The emptiness of space allows it to contain things. The fact that thoughts can come crowding into our mind at will must mean that “mind” is actually an empty space too. If someone were really in residence there, it would surely not be invaded by all these thoughts.
— Yoshida Kenko, Essays in Idleness
We are no more responsible for the evil thoughts that pass through our minds, than a scarecrow for the birds which fly over the seedplot he has to guard; the sole responsibility in each case is to prevent them from settling.
— Churton Collins, aphorisms in the English Review, 1914
This part of the practice should be handled carefully. The fact is that none of your thoughts are “you.” The filters are not necessary. They’re useful sometimes, but not really necessary. Any thought at all can come through your mind and have no effect on it. But the problem is that the ego might decide to try to hang on to those forbidden thoughts and this could cause trouble. That’s why the filters exist in the first place — to keep you from acting on some of those thoughts.
But you can also just let those thoughts come into the conscious mind and still not act on them. That’s harder for most people to do. It takes practice and discipline. But if you can learn to do it you’ll be able to handle a lot of stuff that most people can’t handle very well. You’ll be less likely to be overwhelmed by strong or difficult emotions, for example.
The most useful lesson zazen ever taught me was that my thoughts are just thoughts. All of them. No matter what they are. They’re all just thoughts. No big deal.
— Brad Warner, “Thought Filters“