The fable of the millipede and the songbird is a story about the difference between instinct and knowledge. It goes like this:
High above the forest floor, a millipede strolled along the branch of a tree, her thousand pairs of legs swinging in an easy gait. From the tree top, song birds looked down, fascinated by the synchronization of the millipede’s stride. “That’s an amazing talent,” chirped the songbirds. “You have more limbs than we can count. How do you do it?” And for the first time in her life the millipede thought about this. “Yes,” she wondered, “how do I do what I do?” As she turned to look back, her bristling legs suddenly ran into one another and tangled like vines of ivy. The songbirds laughed as the millipede, in a panic of confusion, twisted herself in a knot and fell to earth below.
On the forest floor, the millipede, realizing that only her pride was hurt, slowly, carefully, limb by limb, unraveled herself. With patience and hard work, she studied and flexed and tested her appendages, until she was able to stand and walk. What was once instinct became knowledge. She realized she didn’t have to move at her old, slow, rote pace. She could amble, strut, prance, even run and jump. Then, as never before, she listened to the symphony of the songbirds and let music touch her heart. Now in perfect command of thousands of talented legs, she gathered courage, and, with a style of her own, danced and danced a dazzling dance that astonished all the creatures of her world. 
The lesson here is that conscious reflection of an unconscious action will impair your ability to do that action. But after you introspect and really study how you do what you do, it will transform into knowledge and you will have greater command of that skill.
That, in a nutshell, is why I blog. The act of introspection — of turning abstract thoughts into concrete words — strengthens my knowledge of that subject and enables me to dance a dazzling dance.
 I got this version of the fable from the book Story: Substance, Structure, Style and the Principles of Screenwriting by Robert McKee, but can’t find the original version of it anywhere (it’s uncredited in his book). The closest I can find is The Centipede’s Dilemma, but that version lacks the second half of the fable.