Or does it? Even if we assume that knowledge is attainable (which it isn’t, as demonstrated by Münchhausen’s trilemma), all knowledge is merely that of our sensory inputs. Things, such as grass, are merely models to describe those senory inputs, but can impossibly be proven correct, since there is always another model which could describe them just as well (easy example: everything is a simulation). Furthermore, there is nothing that says that there has to exist such a model which is reality in the first place.