Isn't "doth" the 3rd person singular? I think "every soul who doth read this" is right, but "they doth return" should be "they do return." In the last verse, it could be "Not every pigeon...hath wings," or "Not all...have," but I doubt you could ever properly say "all pigeons hath wings." If I'm wrong about this point of grammar, please correct me, and I'll apologise.

Quibbles aside, I enjoy it!