Right of the bat in Horton Hears a Who!, Horton starts hearing voices coming from a speck of dust. He's flabbergasted at first (how could a whole town fit on that little speck?!) but soon comes to accept them for how they are. Of course, the other animals in the Jungle of Nool have a harder time accepting that there are folks out there who could live in a different place and in a different way than they do.
Also, come on. People hearing voices? Isn't there a name for that sort of thing?
In any case, we can think about this speck (and Who-ville as a whole) through the lens of both historical allegories.
Even without the historical lens, the tiny clover serves as an important reminder: not everything is done—or seen—the same way for everyone. And our buddy Horton definitely gets it.