Not the kind mixed with fear, but pure sadness.
The adjective pure does not mean it emerges from the vacuum, independently of everything else. There are events happening in specific contexts that trigger such feeling, but once it is here, it might expand and become all encompassing for a period of time.
But its purity is not revealed instantaneously, it takes time. I need to witness the feeling without pushing it or overthink it, no matter how uncomfortable—or even painful—it might be to do so.
I don't feel disconnected from life while experiencing sadness. On the contrary, fully embracing this feeling makes me take life as a whole, too—not only the parts that I like.
But while it last, this burning feeling on my chest is a sort of death and the following grieving process.
Death sounds quite fatalistic, but it is not. Life needs death. Dying means making space for something new.
This might be experienced in subtle ways. For instance, when finding that a personal belief is false, the old person who believed that dies, and a new one who doesn't is born. It is a tiny death that might go unnoticed.
But sometimes leaving a delusional state shakes our world to its core. It leaves a profound emptiness, which
we I call sadness.
Fully experiencing the sadness is allowing such emptiness to exist. If we rush to fill the void with something else because it feels too uncomfortable, a fresh delusion takes the empty. We are numbed and delusional again until the new wrong view couldn't sustain any longer and collapse by itself—because everything lacking truth eventually collapses. Our life goes on and on in circles, and each time we end up at the starting point, the pain is greater.
Fearlessly experiencing the painful sadness is the path of least resistance.