When Nature made the bluebird she wished to propitiate both the sky and the earth, so she gave him the color of the one on his back and the hue of the other on his breast, and ordained that his appearance in spring should denote that the strife and war between these two elements was at an end. He is the peace-harbinger; in him the celestial and terrestrial strike hands and are fast friends. He means the furrow and he means the warmth; he means all the soft, wooing influences of the spring on the one hand, and the retreating footsteps of winter on the other.
~ John Burroughs
(Wake-Robin)