The traits of the solitary bird are five: first, it seeks the highest place; second, it withstands no company; third, it holds its beak in the air; fourth, it has no definite color; fifth, it sings sweetly. These traits must be possessed by the contemplative soul.
It must rise above passing things, paying no more heed to them than if they did not exist. It must likewise be so fond of silence and solitude that it does not tolerate the company of another creature. It must hold its beak in the air of the Holy Spirit, responding to his inspirations, that by so doing it may become worthy of his company. It must have no definite color, desiring to do nothing definite other than the will of God. It must sing sweetly in the contemplation and love of its Bridegroom.
~ The Sayings of Light and Love #121 by St. John of the Cross