Defining Indian summer

"{Indian summer} comes after the early frosts, when the wind is southwest, and the air is delightfully mild and sweet. The sky is then singularly transparent, pure and beautiful, and the fleecy clouds are bright with color. The Indians believed the season to be caused by a wind that was sent from the southwestern god Cautantowwit, who was regarded as superior to all other beings in benevolence and power, and the one to whom their souls went when the departed from the earthly body.''

-- By Sidney Perley, in Historic Storms of New England (1891)