Von Trapp's wife died young. The colonel's approach to the children is simple and brutal. The children are governed according to the requirements of the sailor's drill. Maria develops a strong bond with them.
When the Colonel prepares to leave home for Vienna, Maria and the children rehearse songs, play games, go out in nature, and the family is filled with the sound of music.
When the Colonel returns with the Baroness, whom he intends to marry, he finds that his "sailors" have been trained to be a very educated family choir.
When she sees the Baroness arrive, Maria leaves a letter and returns to the convent, knowing that she will be the new mother of her children. However, the children cannot get along with the Baroness because she is too proper. Meanwhile, Maria arouses the Colonel's love for life and his love for her. So the Colonel rejects the Baroness and goes to the convent to find Maria, and they finally become a happy couple.
This was on the eve of Hitler's annexation of Austria in the 1930s. On the day of the Austrian Folk Music Festival in Salzburg, the Colonel is ordered to Colonel to join the Nazi's navy and is closely watched. Taking the opportunity to attend the folk music festival, the Trapp Family Choir gives their heartfelt songs in front of their fellow Austrians and, with the assistance of friends and nuns, escapes their troubled homeland to the land of the free.
Music and song are a catharsis of emotion; people sing when they are joyful and when they are in pain. The Sound of Music is a musical in which Maria sings incessantly, a bellicose yearning for freedom, yes, freedom, although at first she doesn't realize it.
Freedom is one of the themes of this movie, I think.
A convent is a place to cultivate one's body and mind, kind of like the Taoist temples and monasteries in China, but it's essentially a kind of bondage to humanity, with a lot of rules. Maria clearly does not belong to that kind of place, she loves freedom, likes to run in the vast grass, likes to sing like a bird. This kind of behavior is not understood by the people in the convent, so she feels lost and feels that she has done something wrong and should repent to God. Fortunately, the abbess is a reasonable and respectable person, and we see that she sings as well, which is very melodious. Without this enlightened Mother Superior, Mary would probably have lived a dull and monotonous life in the convent like all the other nuns, and then slowly forgotten any opening of her mouth to sing as the years went by.
The Mother Superior most likely sees in Maria a reflection of her own youth, and so hopes that she does not make the same mistake.
Traditionally, a happy man must have a happy family, and this is especially true for a woman, which is why the innocent, passionate, and beautiful Maria later becomes the captain's wife. In order to show the love between Maria and the captain, the movie arranged the role of the countess. Of course, this countess is also beautiful, understanding, and very rich, it seems to be the best candidate for the captain's wife, but the captain finally chose Maria.