It's a good job these computer things don't have joined up writing or you might have a problem reading this.
How aeroplanes fly.
Air passes over and beneath the wing which causes a difference in pressure due...
ALL aircraft performance and handling is derived from the angle of attack of the wing relative to the air flowing over it. Due to 'an accident of history' the most common way to express that angle is in terms of speed. So to all extents and purposes, aircraft performance, handling and the safety margins which are prudent to observe are based on SPEED.
If this isn't so, please enlighten us.