As a pastor’s kid I was able to witness my dad’s ordination ceremony. It was sort of like a graduation type thing where the church leaders of the denomination declared him as suitable and validated his call by God. It was nice, we had cake. "Hey now", I was little. The Levitical priests ordination was radically different. They surely didn't have cake!
Leviticus 8 gives you a glimpse of a completely different ordination ceremony. Moses says to Aaron that you and all your sons are now special people called priests and you will be the only ones suitable to talk to God. You are responsible for making sure that the sins of the nation are atoned for. You have to slaughter animals, drain blood, burn fat, and wave animal parts around in the air. You have to eat portions what the people give you, because if you don’t eat it all, well then the people’s offering is in vain and not acceptable. This is your job from now on. But don’t worry; you’ll get paid in grain and livestock. Oh, and so the people will know that this is now your responsibility we’re going to have this big ordination ceremony. You’ll get to wear really cool clothes. We’ll slaughter a bull, a ram, a lamb and eat some flat bread with no yeast. There’s just this one part of the ceremony where I’m going to put blood on your right ear lobe, your right thumb, your right big toe and sprinkle blood on your clothes, but I’m sure you won’t mind. Then you have to go to the entrance of the Tent of Meeting for seven days and eat all this stuff we burned. If you leave before the seven days or don’t eat it all,...well...you’ll die. It’s what the Lord told me to do with you and your family, so I’m sure there’s no problem. Sound good? Aren’t you excited! Great, let’s do it!