首楞嚴義疏注經 1.480

1.480

地水火風空輪各對一指，又一一指端有千輪相，故云輪指。屈指問見，意欲推心。

The wheels of earth, water, fire, wind, and space each correspond to one finger, and the tip of each finger bears the mark of a thousand-spoked wheel, hence they are called "wheeled fingers." Bending the fingers to ask about seeing is intended to interrogate the mind.