Was through a practical demonstration of what being arrogant will do.. and that practical demonstration was of Satan.
Just Imagine this situation – You just opened your eyes for the first time, and you see infinite numbers of Angels bowing down (prostrating) infront of you – Because they are commanded by GOD to do so, and out of that Infinite there is One (Satan was not an Angel, he was a Jinn who worshipped GOD day and night) who is standing straight – arrogantly, and a conversation takes place.. between GOD and Satan, and this is going to be your life’s first experience..
(Chapter 7 – Al A’raf, The Elevations )
And it starts by seeing, never ever act arrogant infront of GOD..
If you are a Person who understand things through observations, you will understand it very well..