The grand finale to the film (but don't panic, we have a couple more days of songs to go).
Literally, the family had to climb every mountain in front of them to cross the border, when at last they would be safe. Figuratively, they had a far greater journey and challenge ahead - Maria for example (the real life one) ended up living in the United States I believe.
The symbolism though, that Captain Von Trapp, through his love for his family and Maria was determined to oppose what appeared to be an all encompassing power in the shape of Nazi Germany. Every challenge, every doubt, every day must have seemed like another mountain.
Sometimes, in our lives, even the smallest things seem like an insurmountable mountain. Towering cliffs which appear to be unscalable, crevices too deep to cross - the world is one big challenge. At times like that, maybe it is time to take a step back, look at the wonderment, how far we have come, and what great progress we have made. Then, with careful consideration and planning, to gradually ease forwards again, never being fearful if we need to take a few more steps back to be in a stronger position to move onwards.
Climb every mountain - when you are ready to climb it, and have the right support around you.
Actually, it’s about YOU