"When we have spiritual ego[tism] we have an over inflated sense of our own spiritual ability and understanding. We begin to think that we are somehow unique, that God has told us or given us something that others don't have....We don't ask questions sincerely desiring an answer or direction. Instead we ask a question, already thinking that we know what the answer should be. The problem is that, when the answer comes and it isn't what you were expecting, it can be really hard to humble yourself and accept [it].
"In Numbers 12 it tells how Miriam, and her brother Aaron, both spoke out publicly against Moses for his marriage of an Ethiopian woman. This Ethiopian woman has a fascinating story...and there are several possible reasons for why Miriam and Aaron confronted him about her. I won't go into all of them in this post, but suffice it to say that the real issue wasn't his marriage but deeper doubts that Miriam and Aaron had about his role as the prophet and his ability to receive revelation from God.
"Miriam and Aaron had both been blessed with spiritual gifts, specifically the gift of prophecy. In fact, Miriam's gift was so powerful that she was known as "the prophetess". She had the ability to speak with power and with authority. So when Moses did and taught something that she didn't like she questioned his ability to receive revelation, saying, "Hath the Lord indeed spoken only by Moses? hath he not spoken also by us?" (Numbers 12:2)"
You can read the rest of Heather Farrell's essay on Miriam here: http://www.womeninthescriptures.com/2014/09/miriam-leprosy-and-bad-case-of.html