Let's say a person moves out and leaves some belongings (for instance food, books, other personal items) for public consumption - be it with or without a note that it is for free (why would anyone put his things out like that if not for the purpose of giving it away). But also another example: There is a good knife in one drawer that is in a public kitchen. It is not closed and after I take and use it, I return it in the next morning after washing/cleaning it into its respective drawer.
Living in my current environment it is bound to happen that some things just lay around 'for free'. Am I free to take these things (and maybe, once they served their use e.g books, recyclable items) and offer them for free back again?
What does Chazal say about this. I'm sure that back in those days where there was probably much less privacy and 'private enclosed property' than nowadays, this issue must've been discussed somewhat extensively.