Appreciation of Yin and Lao aerial couplets in past dynasties

My understanding:

Old snow condenses over the years, but it doesn't melt all the year round. How to open it without melting snow in spring?

Yin's voice is nowhere to be found in the air, so how can he make a solid start by shouting slogans in the air?

How can empty slogans get off to a solid start?

If the snow doesn't melt, how can spring bloom?