I hate the Communists and have for many years and don't feel right about giving up my career to defend them. I will give up my film career if it is in the interests of defending something I believe in, but not this.
Any idea can be brought into the classroom if the point is to inquire into its structure, history, influence and so forth. But no idea belongs in the classroom if the point of introducing it is to recruit your students for the political agenda it may be thought to imply.
Think about the photo before and after, never during. The secret is to take your time. You mustn't go too fast. The subject must forget about you. Then, however, you must be very quick.

