I think Cassio’s opinion of feeling that to lose one’s reputation is to lose a critical, even immortal, part of oneself is more valid. Reputation means everything, it's how people see you.
If you have a bad reputation people will see you as someone they don’t like. In addition, if you're a good student and have good grades and you get in a fight, your reputation is ruined.
Mainly people won’t see you as a good student anymore and everything you work towards is over, because you considered a bad student now. Therefore reputation isn’t meaningless as
Iago says. Cassio says, “My reputation, my reputation! I’ve lost my reputation, the longest­living and truest part of myself! Everything else in me is just animal­like. Oh, my reputation, Iago, my reputation!” Above all, his reputation is ruined, he got fired as lieutenant. The one everyone saw as a good guy, is now saw as a drunk and animal­like. Losing his reputation was like losing himself, because he's not a drunk or and animal, one mistake can ruin everything. In contrast, If your reputation was as meaningless as Iago says than Cassio wouldn’t have got fired as lieutenant and saw as a bad person. Iago says, “A reputation is a useless and fake quality that others impose on us. You haven’t lost it unless you think you have. There are lots of ways to get on the general’s good side again. You’ve been discharged because he’s angry, and because he’s obliged to do so for policy reasons, not because