The Dot and the Line: A Romance in Lower Mathematics
This was a favorite of mine as a child. Animated by Chuck Jones and brilliantly designed by Maurice Noble. Straying from the usual Looney Tunes animated shorts, this piece really stood out to me. I remember being amazed at how a story was told using such a simple concept. I later appreciated it for how complicated it was while using those themes. Keep an eye on the backgrounds also, as they are beautiful in their abstract placement and design.
Do take a moment to watch or re-watch if you have a moment.