It is the absence of every thing, you see, because «things» are made of matter. (religion-online.org)
Noting the absence of things is common at this age, such as «all gone milk.» (babycenter.com)
I think it's more about being present and your surroundings being comfortable so as a result there is an absence of things that cause stress, aka clutter and things that don't bring joy. (lyndeestylesca.com)