I agreed with Erasmus' rules listed in "On the Right Method of Instruction" (page 47 in Philosophical Documents). I think that writing and thinking go hand in hand. Many teachers ask their students to record thoughts, questions, ideas, and reflections in a journal so that they might think through their reactions to the course material. I am an English/Secondary Education major, so I think I would like to ask my future students to discuss their reactions to a film or work of literature in their journals before we begin a full class or small group discussion.
I tend to doubt the usefulness of Latin and Greek to a modern student, although I can see how Erasmus would have considered this a necessary field of study. The study of a modern foreign language can give a student skills useful in their everyday life and expose him or her to a different culture's literature (which I think is keeping with Erasmus' goals). For example, as a future teacher it would benefit me to speak Spanish so I could communicate more effectively with students and their parents who are native speakers of Spanish.
Erasmus makes a strong point on the teaching of grammar. Although he writes specifically of grammar as it relates to learning a foreign language, his method can be applied to English grammar as well. Recent research has shown that isolated grammar study is ineffective in making a student a better writer. The URL below lists research on teaching grammar in context. While this is of particular interest to me as a future English teacher, I believe that all teachers could benefit from this infomation (especially as writing across the curriculum programs gain popularity in many schools).