So says the great 14th century sage Tsong Khapa.
Even if you know this, even if you know this with a large part of your heart, life is still difficult, at minimum, sometimes. It seems that we often don't want to be at peace, or we can't, either because our inside world or the outside world will not let us. ...however if you look at the 'outside obstacles' for long enough, you might find internal ones behind them.
So one problem is being tricked into thinking a problem is coming from outside. For example, my partner drives me bonkers. (Or dating. Or not dating.) Or something like what happened recently, a waiter spilled (a lot of) salad dressing on my leg. It's another kind of suffering to know that the primary cause cannot be outside, to see that and to lack the drive or discipline to act on that knowledge.
Sometimes knowledge is unable to serve it's function, it just tortures you, you cannot align with it, it cannot link with the core of your life, your soul says no. Then knowledge stays on the surface, making some experiences seem right and others wrong. It makes you want to do something with your life, improve things, be busy, tackle problems, gain insight. Or feel like you should. We build a castle of our desires - even spiritual ones - then lock ourselves inside it.
So there's the suffering of, say, my 78 year old mom, who is angry that her brain is shutting down. There's the suffering of witnessing seeing someone you love deny reality. There's the suffering of having the life that you want but being somehow or at least occasionally unable to move within it. There's the suffering of thinking there's something wrong. There's the suffering of looking around and feeling that you should be happy, or happier. The suffering of trying to compulsively think our way out of pain.
The most basic suffering perhaps is that, again and again and again, things are not how we think they are supposed to be. There aren't supposed to be long lines, people aren't supposed to disappoint us, death, cancer, depression definitely shouldn't happen. We get buyer's remorse, we rationalize, we do things we think we shouldn't and then explain to ourselves or others why...focused internally or externally. We tell ourselves why things don't match up. "I'll start tomorrow." "Traffic is bad - maybe there's a football game." "I could never do that." We explain to our friend why it's OK to lie in this case. We justify, blame, or deny. Not accepting the continuous reality of life is the ultimate addiction, the ultimate cognitive dissonance.
The thing I come back to over and over again: Whatever is happening now is how things are. It might be painful, but it is not a mistake, not an accident. It's life. The only appropriate response to how things are is an embrace.
It's appropriate because it means we will stop fighting. Rather, that we will accept and then in some way move toward positive change, but we put down the sword, we take off the blinders and the any-colored glasses and the veils. We shift the balance a little more toward what things are, what we are, and a little less toward what we simply wish them and ourselves to be.
Because we want to relieve suffering, because we want to progress - doesn't mean there is anything wrong. We must act and change things from the foundation of 'nothing is wrong'. And from that place we find - for at least that moment - the human body at peace with itself.
“A flower falls, though we love it; and a weed grows, though we do not love it.”