Airspeed can be converted to altitude, or altitude converted to airspeed with varying levels of efficiency - you can convert one to another depending on terrain, weather, endurance, range, conditions of flight, configuration etc...

I'd never thought about planes this way, as great transformers of one form of energy into another, storing potential energy in altitude. Very cool post!

Then read. And read some more, and more, and more...

I stayed up tired as I was, sat on the hotel room bed for NINE HOURS. NINE HOURS STRAIGHT.

Do you remember what you read? I'm curious about where the internet took you then.