"The Lord said to Aaron, 'Go into the desert to meet Moses.' So he met Moses at the mountain of God and kissed him. Then Moses told Aaron everything the Lord had sent him to say, and also about all the miraculous signs he had commanded him to perform." NIV translation
God called Aaron to meet Moses and so begins a pattern that will occur over and over in the Bible. It is at this point that God begins to send His people in groups of two to accomplish His will. This was repeated when Jesus sent out the disciples two by two (see Luke 10). It will be repeated again in the last days with the appearance of two witnesses in Jerusalem (see Revelation 11).
"Moses and Aaron brought together all the elders of the Israelites, and Aaron told them everything the Lord had said to Moses. He also performed the signs before the people, and they believed. And when they heard that the Lord was concerned about them and had seen their misery, they bowed down and worshiped." NIV translation
They called a meeting of the Israelites and Aaron spoke the words of God and demonstrated the signs. In so doing he showed the people the heart of God for His people. The people's hearts were touched and they reacted by bowing in worship.
This is a picture of how we are to carry out the Great Commission. We are to tell people of God's love for them as demonstrated by sending His Son to die for them. As with Moses and Aaron, He has also given us signs to demonstrate that love and power. They were called to lead the people out of their slavery in Egypt while we are called to lead the people out of their bondage to sin and death. That, my friends, is the heart of the matter!