In my very early days as a student, I had this drilled into me: "Stick controls airspeed, throttle controls altitude". Of course, the machine weighted about 15 pounds per horsepower.
Today's airliners are so overpowered, that the relationship can be reversed, and indeed the automatics do the opposite: Autothrottle controls airspeed, autopilot controls altitude.
And when you fly in this mode leg after leg, the basic principle in my first paragraph - if not completely forgotten - might not be readily called up from long-term cranial storage when it's really needed.
