What is stillness?

[Patrick]

I learned how to remain untriggered while remaining myself from Tolle.

Stillness is a "State of Mind"?

The old metaphor, "Stillness as in a still pond".

"While remaining myself" means that this stillness is present even while I am interacting with someone that is turbulent emotionally. The more obvious stillness state is the one we normally experience in meditation. But having this inside you while interacting with others takes a different type of presence. You are basically witnessing your mental body react to the turbulent interaction, instead of thinking that this mental body is you. So you can reach a type of detachment.