“When the blood is made dull with the act of
sport, there should be, again to inflame it and to
give satiety a fresh appetite, loveliness in favour,
sympathy in years, manners and beauties; all which
the Moor is defective in: now, for want of these
required conveniences, her delicate tenderness will
find itself abused, begin to heave the gorge,
disrelish and abhor the Moor; very nature will
instruct her in it and compel her to some second
choice.”-Iago

This quote by Iago does a good job explaining how he believes that what Desdemona wants is a good looking man.  With Othello getting older and with the stress of wars his beauty will soon be gone and she will have to fall back to her second choice.  This generalization assumes that women only want men that are good looking and he uses this idea for his own self serving purposes. Iago is trying to find any way possible to convince Roderigo that his plan will work to make Othello believe Desdemona is having an affair.

“yet that I put the Moor At least into a jealousy so strong That judgment cannot cure.”-Iago

This quote by Iago again goes along with the idea that the Moor is a trusting man who will believe almost anything people tell him because at heart he sees the good in people. Once Iago puts the idea that his wife is sleeping with someone else, Iago is sure Othello will believe just based on who he is and the trusting nature he has. This jealousy will cause doubt in Othello and drive him crazy.  This generalization from Iago factors into his plan on how he will take advantage of him for his own agenda.