Rhinos have a built-in capacity for Euphoria that defies description. It just comes with the Natural Package. We do not control it, because… Well, why would We want to?
Some days are only a #1 on the Euphoria Scale, others are a #3. These vacillations are more or less meaningless; any way you look at it, We are of Good Cheer and excited by our Prospects. Dazzled by our Good Fortune.
Maybe other Critters have the same potential, but forget to notice it.