וָאֵ֖רֶא הַחַיּ֑וֹת וְהִנֵּה֩ אוֹפַ֨ן אֶחָ֥ד בָּאָ֛רֶץ אֵ֥צֶל הַחַיּ֖וֹת לְאַרְבַּ֥עַת פָּנָֽיו׃
Now as I beheld the living creatures, behold one wheel at the bottom hard by the living creatures, at the four faces thereof.
Read Jewish philosophical commentary on Ezekiel 1:15: and classical philosophical sources.