There are patterns in the sounds of the melody (Happy Birthday to You, and Twinkle, Twinkle Little Star), There are patterns in the ways the fingers are used (chords in the key of D and the key of A feel the same). Three are patterns in chord progressions (Pachelbel's Canon in D). There are patterns in repetition of theme (Beethoven's Ninth Symphony). Finding the patterns is good exercise for the ears and the mind.