Great people....great minds....think great thoughts. Little minds can be sidetracked or distracted by petty, immaterial things. It's a "not so nice" way of saying someone is petty, immature or simple.
i use to like this man that i dont know but i see him around my house and he sees me and at one point we would make eye contact but he did approch me so feeled as if he was not entrested in me