Objects have feelings. They are not the feelings of those objects, of course, they are our own feelings that we associate with the objects. Generally speaking, nice objects evoke positive feelings, and ugly or scary objects — negative. Of course it's more complicated than that, there is a million shades and kinds of feelings we have, and they also depend on the context and evolve over time. But every object we notice gets automatically assigned an emotional value — the objects that don't cannot be noticed.
It is the goal of art to play on those values. Artists create objects that produce in us especially strong and elaborate feelings. The stronger the value, the easier the object is to notice, and art will often pop out, attract your attention. Objects with low value disappear, blend with the background, become less than invisible — they become irrelevant. It's the objects with value that we want to see, interact with, or own. The emotional value gives objects their meanings.
Note, however that the meaning doesn't have to come from the object's appearance (although it usually does on initial discovery): it can come from a story that we have heard about it, its importance to other people, cultural connotations, market value, or... usefulness.
That's where the distinction between tools, toys and treasures comes in. Toys are shiny, engaging, immediately valuable objects that are desirable for their ability to entertain us. They may be child's toys, or they may be books, movies, paintings, fireworks shows, computer games, news items, gossips, board games, or sport accessories. Treasures are not engaging by themselves, but take their value from cultural references, market value or the status that they are a sign of: money, famous works of art, precious metals and gems, sport cars, fashionable clothes, jewelry. Tools, finally, are neither engaging nor expensive, and have very little value of their own — they are often overlooked when scanning the interiors — but their value comes from what they enable you to do: actual tools, appliances, vehicles, prosthetics, communication devices, measuring utensils, uniforms, badges, permits, protective gear, medical supplies, or documentation and manuals.
Of course the world is not black and white, and in practice every object is a bit of everything. Almost everything in our capitalistic world has a price today, so it's a bit of a treasure. Toys can helps us learn or make us fit, so they are useful. Expensive things are often also nice and make us happier, and the status they signify can be useful. And finally tools can give us a lot of pleasure when used for hobby. But often the principal purpose of an item will fall in one of those categories (then again, there are things like musical instruments, which are all three equally).
Why am I writing this? It's because I think it is very important, when designing something, to always remember in which category it primarily falls, and design it accordingly. A tool should not cry for our attention, should not require us to focus on it, it should not be something we interact with — rather it should disappear and become a seamless extension of our bodies. An art piece on the other hand should try to get all the attention it can, using one strategy or another. Treasure needs no design at all, of course.