There is nothing in nature that expresses more the pure embodiment of joy-absolute freedom from care and grief-unalloyed brimming-over happiness- than the song of a bird. It may be the tipsy, bubbling song of the wren stopping for a melodious moment in his mad . scramble for bugs among the vines on your back porch; it may be the fullthroated whistle of the gorgeous cardinal signalling for . a mate to share the claim he has staked out among the maples of "The Knoll;" or perhaps it chances to be the sweet gurgle of the eaves-martin from his mud jug of a nest plastered high up under the eaves of the barn.