Need to know where this quote is from, and what it was. Thanks!

Field Marshal Helmuth von Moltke: 1866

“The war of 1866 [between Prussia and Austria] was entered on not because the existence of Prussia was threatened, nor was it caused by public opinion and the voice of the people; it was a struggle, long foreseen and calmly prepared for, recognized as a necessity by the Cabinet, not for territorial aggrandizement, for an extension of our domain, or for material advantage, but for an ideal end--the establishment of power. Not a foot of land was exacted from Austria, but she had to renounce all part in the hegemony of Germany. . . Austria had exhausted her strength in conquests south of the Alps, and left the western German provinces unprotected, instead of following the road pointed out by the Danube. Its centre of gravity lay out of Germany; Prussia's lay within it. Prussia felt itself called upon and strong enough to assume the leadership of the German races.”