Anyone whose goal is 'something higher' must expect someday to suffer vertigo. What is vertigo? Fear of falling? No, Vertigo is something other than fear of falling. It is the voice of the emptiness below us which tempts and lures us, it is the desire to fall, against which, terrified, we defend ourselves.

This quote is referring to the feeling of vertigo, which is a type of motion sickness where one has the sensation of spinning, or falling. It can be caused by looking down from a great height, like from a tall building or mountain. The quote suggests that anyone whose ambition is to achieve something greater than themselves may experience vertigo as they work towards their goal. Vertigo can be seen as a voice that tempts and lures us to give up, and it takes courage to fight the feeling and go for what one desires.