To obtain a certain spiritual level in Aikido.
I believe that O-Sensei gave us Aikido as a vehicle to a better self.
I strongly believe that you must thoroughly and systematically go through the physical side of Aikido for many many years to have the possibility of reaching the spiritual side.
If you rush, take short cuts, or pretend to understand when you do not, you will only fool yourself.
If O-Sensei wanted us to just become spiritual beings, he would have given us chants, prayers, or some other method to obtain that.
Work through the physical side of Aikido with passion and commitment. As you become more skilled (enlightened), so shall you gain a better insight and understanding of what O-Sensei had in mind for us all.
Aikido is so much more than just a martial art. Enjoy the journey.