So, first you have to be able to play with a metronome. Then you take your freedom. If you play in an orchestra, you got to watch the conductor, he is like a metronome, but it is more difficult because he can change rhythms. ↗
I give bird songs to those who dwell in cities and have never heard them, make rhythms for those who know only military marches or jazz, and paint colors for those who see none. ↗
Music rhythms are mathematical patterns. When you hear a song and your body starts moving with it, your body is doing math. The kids in their parents' garage practicing to be a band may not realize it, but they're also practicing math. ↗
In a broader sense, the rhythms of nature, large and small - the sounds of wind and water, the sounds of birds and insects - must inevitably find their analogues in music. ↗