Easy etymology of “prejudice” breaks it down into pre-judge. Truthfully, prejudice often occurs without our being aware of it and may even lean toward a positive as well as a negative.
During the past two years, I have delved into the extensive Ezra Jack Keats archives in the de Grummond Children’s Literature Collection at the University of Southern Mississippi. Talkative nerd that I am, I’ve shared the excitement of my “finds” with anyone who would listen. [I’ve noticed some people can listen and roll their eyes at the same time.] It’s been interesting how many people have been surprised to learn that Keats was Jewish. “I thought he was Black!”
Logic forms the basis for this pre-judgment. Most people realize that Keats made a Black child named Peter the protagonist for his picture book The Snowy Day at a time when this was an innovation. Their assumption is that the author must have been Black to think about it.
While that assumption is wrong, Jack did experience and understand prejudice beginning when he was quite young. He learned during his school days that teachers and neighbors were fearful of what might be contained in gifts of food from a Jewish kitchen. I was astounded at his story of taking a decorated cake to his school principal – his father’s attempt to compensate for Jack's many sick-day absences from school. Only after Jack assured the principal that it was “bought” rather than homemade did she accept the cake.
The episode brought back memories of a different kind of pre-judgment based on smell from my second grade teaching days. On student report card conference day, an aroma preceded Becky’s Korean mother as she headed to my room. I pre-judged that something good was on the way. When Mrs. Peach’s turn came for her conference, she set a plate on my desk – piled high with spring rolls still hot from the stove. 
“I know Becky’s doing fine,” she said. “Eat one now and take the rest to your family for supper.” I ate the delicious spring roll and assured her that her assessment was correct. Becky was indeed an excellent student.
Remembering how much my family enjoyed stepping out of their Southern “chicken and dumplings” box for supper that night, I felt sad for the teachers, neighbors, and principal who were afraid of Jack’s mother’s food. According to those who knew, she was an excellent cook.
Who knows how many things we miss when we consciously or unconsciously make a decision based on pre-judgment? Unless, of course, the preconception is based on something as solid as an aroma.