let there be an effect on you, and there by having affect on them.

What I think that this means is that when reading someones work in your writing community let it change something in you, so that it has an effect on you and to show that you care. If someone know that you care, they are more likely to listen to what you say and let you affect them in what they do. A student will listen to you, if you listen to them and hear what they say. Someones writing can say a lot about them as a person and what is going on in their life. Teaching will be a lot easier on you, if the student's life have an effect on you. If you do not care about them, they will know and they will not want to hear what you have to say, so you will not get anywhere as a teacher. As a teacher you have to see what is going on with your students and if not you do not have a classroom, you have a group of students.