I've been meditating today on the title of Mary given in the Litany of Loreto as "The Tower of David", the Turris Davidica. It is a mystical appeciation of the Virgin Mary as a tower of refuge and strength against the enemy.
It is an idea which entered church thinking in the Middle Ages, as is outlined in this ebook from Project Gutenberg by Dr. John R. Effinger, written in 1907:
In the eleventh century, the successful struggle which had been made by Gregory VII., with the aid of the Countess Matilda, for the principle of papal supremacy exerted a marked influence upon the religious life of the time and gave an undoubted impetus to the idea of conventual life for women, as during this period many new cloisters were established. It will be readily understood that the deeds of the illustrious Tuscan countess had been held up more than once to the gaze of the people of Italy as worthy of their emulation, and many women were unquestionably induced in this way to give their lives to the Church. In the Cistercian order alone there were more than six thousand cloisters for women by the middle of the twelfth century.It was during this same eleventh century, when a woman had helped to strengthen the power of the Church, that the influence of the Madonna—of Mary, the mother of Christ—began to make a profound impression upon the form of worship. A multitude of Latin hymns may be found which were written in honor of the Virgin as far back as the fifth century, and in the mediæval romances of chivalry, which were so often tinged with religious mysticism, she often appears as the Empress and Queen of Heaven. All through the mediæval period, in fact, there was a constant endeavor to prove that the Old Testament contained allusions to Mary, and, with this in view, Albertus Magnus put together a Marienbibel in the twelfth century, and Bonaventura edited a Marienpsalter. Therein, the gates of Paradise, Noah's ark, Jacob's ladder, the ark of the Covenant, Aaron's rod, Solomon's throne, and many other things, were held up as examples and foreshadowings of the coming of the Blessed Virgin; and in the sermons, commentaries, and homilies of the time the same ideas were continually emphasized. A collection of the Latin appellations which were bestowed upon the Madonna during this time contains the following terms, which reveal the fervor and temper of the age: Dei genitrix, virgo virginum, mater Christi, mater divinæ gratiæ, mater potens, speculum justitiæ, vas spirituale, rosa mystica, turris davidica, domus aurea, janua cœli, regina peccatorum, regina apostolorum, consolatrix afflictorum, and regina sanctorum omnium.
A pretty good summary of the concept's imagery can be found here:
The main characteristic here is that of a sturdy tower surrounded by fortifications, hung with many shields and build on rocky foundations.The medallion superimposed on the tower shows the half-image of Mary in the posture of the young and meek Orante. The medallion is decorated with the tools and symbols of war: sword, banner, helmet, shield, trumpet. . .even what looks like the head of Holofernes.
The symbol of the Tower of David is taken from the Song of Songs 4:4. It was applied to Mary, and symbolizes Mary's womb giving life and protection to Jesus (Richard of St. Laurent). Mary also gives protection to all those who seek refuge against temptation and danger (Abertus Magnus). The tower is further a symbol of Mary's undefiled virginity (Salzer 12:21), later also of her Immaculate Conception. The fortifications of the tower are a symbol of Mary's virtues, the many shields (1,000 shields) are virtues or signs of heavenly protection against the devil.
Using Psalm 61, this illustration paraphrases the following verse and attributes it to Mary, "You are a tower of strength against the foe" (Psalm 61:4).
I've been looking for some mediations on it from great Catholic thinkers; I've found this from Cardinal John Henry Newman:
A TOWER in its simplest idea is a fabric for defence against enemies. David, King of Israel, built for this purpose a notable tower; and as he is a figure or type of our Lord, so is his tower a figure denoting our Lord's Virgin Mother.She is called the Tower of David because she had so signally fulfilled the office of defending her Divine Son from the assaults of His foes. It is customary with those who are not Catholics to fancy that the honours we pay to her interfere with the supreme worship which we pay to Him; that in Catholic teaching she eclipses Him. But this is the very reverse of the truth.
For if Mary's glory is so very great, how cannot His be greater still who is the Lord and God of Mary? He is infinitely above His Mother; and all that grace which filled her is but the overflowings and superfluities of His incomprehensible Sanctity. And history teaches us the same lesson. Look at the Protestant countries which threw off all devotion to her three centuries ago, under the notion that to put her from their thoughts would be exalting the praises of her Son. Has that consequence really followed from their profane conduct towards her? Just the reverse—the countries, Germany, Switzerland, England, which so acted, have in great measure ceased to worship Him, and have given up their belief in His Divinity while the Catholic Church, wherever she is to be found, adores Christ as true God and true Man, as firmly as ever she did; and strange indeed would it be, if it ever happened otherwise. Thus Mary is the "Tower of David."
I know a lot of Protestants are wary of Marian devotions because they feel it leads to Mary worship, and idolatry, but I have never found that to be the case. I think that meditating on the life of Mary and the devotion she held for her son is a great way of coming to understand Christ's love for us. I do not believe she is idle in Heaven; and to venerate her is to honor Him whom she accepted, gave birth to, raised, followed, interceded with (specifically at Cana), tended lovingly after his death on the cross, and whose Holy Spirit she received with the Apostles at Pentecost.
I believe she truly was, and is, a tower of strength.