This is something that becomes clearer over time, especially through exploring specific issues through inquiry.
Behind anger, sadness, and compulsions is fear. Behind fear is caring. And behind that caring is love.
Said more succinctly:
Behind identifications (beliefs, velcro) is fear, and behind that fear is caring and love.
The pitfall in saying to so simply and succinctly is that the mind thinks it gets it and that such a superficial and intellectual understanding is sufficient. The benefit is that it can serve as a question to explore, and a guide when we work on ourselves and clients.
A few more details:
Identifications (holding a thought as true) is what creates stressful experiences such as struggle with anger, sadness, and compulsions. (Anger, sadness etc. can also just be here without any struggle.)
Fear is what holds identifications in place. It may be what created the identification in the first place, and it’s often what comes up when the mind considers not having that identification.
Behind fear is a deep caring. A caring for oneself and others. And caring is just another word for love.
When we see the behind all this is love, there is less of a struggle with it. And less struggle means a bit more space around it, which helps soften and release the identifications in and relating to it.