ABSTRACT
As fluids are an important part of natural environment, it can be expected that humans, as well as other animals, have the ability of picking up information about their properties. One aspect of fluids which makes them decisively different from solid objects, is their relation to vessels. They have no form of their own, but “borrow” it from the vessel that contains them. Their form also easily changes when the vessel is moving, (cf. what may happen when you move a glass with liquid.)
