The frequently used explanation of the aerodynamic lifting force using Bernoulli's law is shown to have fundamental drawbacks and incomplete reasoning. On the other hand, an explanation based on repulsion forces is shown to be complete, easier to assimilate, more powerful, and better related to the basic principles of mechanics. Furthermore, it is shown that the high streaming velocity at the upper side of the aerofoil is not the reason for the low pressure. To the contrary, the low pressure generated by the aerofoil is the reason for the high streaming velocity.