"Joy, in Nature's wide dominion, Mightiest cause of all is found; And 'tis joy that moves the pinion When the wheel of time goes round. "


It seems to be this one, from the poem "Hymn To Joy". At least it was the closest I could find.

Found this Schiller quote at the web reference:
"Joy is the mainspring in the whole
Of endless Nature's calm rotation.
Joy moves the dazzling wheels that roll
In the great timepiece of Creation."

From the 2nd web reference:
"Joy Is the mainspring in the whole
round of everlasting nature: joy moves
the wheels of the great timepiece of the
world; she it Is that loosens flowers
from their buds, suns from their firmaments,
rolling spheres in distant space
seen not by the glass of the astronome~.~
Schiller."

And from a 3rd source ( http://earthstep.org/joy!.htm ):
"Joy is the mainspring in the whole of nature's endless calm rotation. Joy moves the dazzling wheels that roll in the great timepiece of creation." Johann Christoph Friedrich von Schiller