What is the main topic of "marine labor"?

Labor at Sea is the work of the French writer Hugo. Hugo once had the following views in the preface of Marine Labor: human beings face three fates, religious, natural and legal; Correspondingly, human beings also have three major struggles, namely, the struggle against religion, the struggle against nature and the struggle against secular laws. Based on this understanding, Hugo tried to reveal the fate of 1 in Notre Dame de Paris, the second fate in Marine Labors and the third fate in Les Miserables.

The story of "Marine Laborers" takes place in Gaines Island. Giriat, the hero, is a young worker who lives by fishing and farming. He fell in love with Druchet, the niece of the shipowner Legelli, and was opposed by Legelli. After Ledger was kidnapped by his partner Han Dan, in order to regain his strength, he bought a new steamboat for transportation and hired Kriban as the captain. When Han Dan killed the sentry and stole the huge sum of money to escape, Kriban took the huge sum of money with a gun. Kriban carefully planned the steamboat to hit the rocks in the fog, creating the illusion of martyrdom and preparing to escape, but was injured by an octopus at sea and buried at the bottom of the sea. The legend lost his beloved steamboat and was in great pain. He claimed that whoever could salvage the intact machine from the bottom of the sea would marry his niece. In order to get the ideal marriage, Giriat went through all the hardships alone. After two months of extremely hard work and tenacious struggle, she finally created a miracle on earth and brought the machine back. Ledger fulfilled his promise and agreed to marry Gillette on behalf of the law. At this time, Giriat discovered that modern law Si Nuo fell in love with a young priest. In the spirit of self-sacrifice, he gave up the right to marry Druchet, perfected her marriage with young priests and helped them leave home. When the young couple set out, he sat sadly on the rocks by the sea, submerged in the rising tide.

Most chapters in the novel are devoted to the character Giriat, and only describing his thrilling hard work on the island accounts for 1/3 of the book. Hugo allowed his hero to work miracles on earth under unimaginable conditions. Giriat's labor was sublimated by the author into a great force enough to resist any great natural forces and finally defeat them. Giriat is virtuous and helpful, which is in sharp contrast with Han Dan, Kriban and others.