There is a famous quote of St. Vincent de Paul:

I wanted to know more: why a dove? What is simple about a dove?

An earlier reference is found in the Gospel of Matthew:

“Behold, I send you forth as sheep in the middle of wolves: be you therefore wise as serpents, and harmless as doves.” – Matthew 10:16

A web search reveals that like some other birds, doves (scientific name: Columbidae) have no gall bladders. Some medieval naturalists concluded they had no bile (gall), which in the medieval theory of the four humours explained the allegedly sweet disposition of doves.

Koninklijke Bibliotheek, the Dutch National Library

Eucharistic Dove, early 13th century. Used for storing communion wafers, doves such as this were suspended above the altar to signify the presence of the Holy Spirit at the Mass. The wafers were stored in a cavity under a hinged lid on the bird’s back.

There’s more… from a website about the symbolism of animals in the Middle Ages:

Isidore of Seville [7th century] (Etymologies, Book 12, 7:61-62): “Doves (columbae) are tame birds that live in company with men; their necks change into different colors, they have no gall, they are often in the nests and make love with a kiss. Ring doves (palumbes) are chaste birds; if it loses its mate it lives alone and never takes another.”

Bartholomaeus Anglicus [13th century] (De proprietatibus rerum, book 12): “The culvour is messager of peace, ensample of simpleness, clean of kind, plenteous in children, follower of meekness, friend of company, forgetter of wrongs. The culvour is forgetful. And therefore when the birds are borne away, she forgetteth her harm and damage, and leaveth not therefore to build and breed in the same place. Also she is nicely curious. For sitting on a tree, she beholdeth and looketh all about toward what part she will fly, and bendeth her neck all about as it were taking avisement. But oft while she taketh avisement of flight, ere she taketh her flight, an arrow flieth through her body, and therefore she faileth of her purpose, as Gregory saith. Also as Ambrose saith, in Egypt and in Syria a culvour is taught to bear letters, and to be messager out of one province into another. For it loveth kindly the place and the dwelling where it was first fed and nourished. And be it never so far borne into far countries, always it will return home again, if it be restored to freedom. And oft to such a culvour a letter is craftily bound under the one wing, and then it is let go. Then it flieth up into the air, and ceaseth never till it come to the first place in which it was bred. And sometimes in the way enemies know thereof, and let it with an arrow, and so for the letters that it beareth, it is wounded and slain, and so it beareth no letter without peril. For oft the letter that is so borne is cause and occasion of the death of it.”

And, of course, the dove is associated with the Holy Spirit. God sent His spirit in the form of a gentle dove to gather us into His church.

Quotes of St. Vincent

From Fr. Robert Maloney, C.M.:

St. Vincent gives a whole series of motives as to why his Vincentian Family should practice simplicity:

• God communicates with the simple (CR II, 4; II, 377; XII, 140).
• God himself is simple; so where simplicity is there God is too (XI, 50).
• The world loves simple people (XII, 142, 152).
• Missionaries especially ought to love it (XII, 157), since it will help
  them in dealing with simple people.
• It is the spirit of Jesus Christ (IV, 393, 481).
• God wants the Community to have this virtue (XII, 150, 246), especially
  since it lives in a world that is filled with duplicity.
• Duplicity is never agreeable to God (IV, 471).
• It is the simple who keep the true religion (XII, 142).

Source: The way of Vincent de Paul: five characteristic virtues

Reflection

• Do I always speak the truth?
• Do I say things as they are or as I want them to be?
• What causes me to conceal or hide something from another?

(from Maloney, Five Missionary Virtues presentation)

Dove diagram: 13th century