It's the universal symbol for a restless mind. The Fool recognizes the tendency well.

He considers Devin in fond, contemplative silence for a second or two more before bringing up his own tea for a sip. The warmth and familiarity of it couple nicely with the gentle affection newly burgeoned in his heart; yes, he thinks, this is good, and right, and worth the risk. A moment later, he steps near enough to Devin to kiss the corner of his mouth--simply because he can--and then drops one hand down to settle against his arm.

"Come sit at my work station," he invites him, gesturing with his tea cup towards the window. There's a glint in his eye when he looks back again. "I shall teach you how to make oil-varnish."