The bird represents the wayfarer of the sky, and at the same time it represents a being who though it belongs to the earth it is capable of dwelling in the skies. The former explanation of the bird represents the idea of a soul whose dwelling place is heaven, and the latter represents the dweller on earth being able to move about in the higher spheres; and both these explanations give the idea that the spiritual person is the inhabitant of the heaven and is only dwelling on the earth for a while.
The pigeon is used as a messenger, to carry a message from one place to another, and therefore the symbol of the dove is a natural one to represent the messenger from above. Spiritual bliss is such a wonderful experience that if a bird or an animal were to have it would never return to its own kind. But it is to the credit of humans that after touching that point of great happiness and bliss they come back into the world of sorrows and disappointments and deliver their message.
This quality can also be seen in the pigeon: when the pigeon is sent it goes, but faithfully comes back to its master. The spiritual person performs their duty doubly: they reach higher than the human plane, touch the divine plane and bring the message from the divine to the human plane. In this way instead of remaining on the divine plane they return to be among their fellow humans for their welfare, which is no small sacrifice. Besides they perform a duty to God, for whom they bring the message they deliver to humanity.
They live as human beings, subject to love, hate, praise and blame; they pass their life in the world of attachment and the life that binds them with a thousand ties on all sides, and yet they do not forget the place whence they come, and they constantly and eagerly look forward to reaching the goal for which they are bound. Therefore in both these journeys, from earth to heaven and from heaven to earth, the idea of the dove proves to be most appropriate of all.