What is the significance of the title "Fiat Voluntas Tua" (a quote from the Latin "Our Father") as a section title in A Canticle for Leibowitz?

Question

When Walter M. Miller Jr. originally wrote the novelettes that he later fixed up to become A Canticle for Leibowitz, they were titled:

• "A Canticle for Leibowitz" (The Magazine of Fantasy and Science Fiction, April 1955)
• "And the Light Is Risen" (ibid., August 1956)
• "The Last Canticle" (ibid., February 1957)

For the 1960 novel release, he apparently did a great deal of rewriting, and one of the most obvious changes he made was to the titles of the sections. They became:

• Fiat Homo
• Fiat Lux
• Fiat Voluntas Tua

and I have always been somewhat puzzled by the title he chose for the third part of the story.

The second section title is a very famous piece of scripture, from Genesis 1:3.

Vulgate: Dixitque Deus: Fiat lux. Et facta est lux.

King James Version: And God said, Let there be light: and there was light.

"Fiat homo" does not similarly appear in the description of the sixth day of creation, but its meaning as a section title seems pretty natural. The first part of the story takes place in a period in which human civilization had retreated back into a dark age, and the reader is shown the fate of the surviving humanity. Mankind exists, but without the light of knowledge. That light—literal and metaphorical both—comes only with the Renaissance-like setting of "Fiat Lux."

However, I have never understood the significance of the third section title: "Fiat Voluntas Tua." The origin of the words is certainly clear; it comes from the Latin text of the "Our Father".

Pater noster, qui es in cælis;
sanctificetur nomen tuum:
Adveniat regnum tuum;
fiat voluntas tua, sicut in cælo, et in terra.
Panem nostrum cotidianum da nobis hodie:
Et dimitte nobis debita nostra, sicut et nos dimittimus debitoribus nostris:
et ne nos inducas in tentationem: sed libera nos a malo.

King James Version: Our Father which art in heaven, Hallowed be thy name.
Thy kingdom come, Thy will be done in earth, as it is in heaven.
Give us this day our daily bread.
And forgive us our debts, as we forgive our debtors.
And lead us not into temptation, but deliver us from evil:

A reasonable translation (following partially the traditional English text), "Fiat voluntas tua," would be, "Let thy will be done." I just don't understand what the significance of that line from the "Pater Noster" is supposed to be. How is it related to what happens in the last segment of the book?

Answer 1

The last segment is open to some interpretation.

“Let thy will be done” is traditionally recognition that it is the will of God that should be done in the world, not man's will, because God is the one who created the heavens and the earth, man, and everything else in it that has life. Setting issues of predestination aside, the title may be intended to reflect all that happens is God’s will.

So what happens?

Primarily, the fleeing of humanity into space might symbolize a new beginning, but it's no guarantee. Will the cycle finally be broken when humanity moves into space, or will it merely repeat itself on a cosmic scale? Will our hopes for humanity's progress amount to nothing? Will the saving of Memorabilia be a blessing to allow mankind to survive or will it curse them to repeat their destruction throughout the stars? But man’s future is not all.

The Earth survives on without man; also God’s will being done.

The shark survives, able to dive to the drpths of the clean water — a creature that has survived on Earth an estimated 200 million years:

shark swam out to his deepest waters and brooded in the old clean currents...

Life on Earth will survive.

The Earth survives man, and man is given a hopeful new lease on life.

Thy (God’s) will be done.