A few days before the start of the new school year I heard these unforgettable words: "It costs the same to teach a bad lesson as a good lesson".
It was Gillian Shephard talking on BBC Radio 4 and her words have rankled with me ever since. How untrue and demoralising. Untrue because it is obviously cheaper to teach a bad lesson.
First, the school management can produce a bad lesson quite cheaply by not hiring the specialist teacher required to teach a good lesson.
Second, it definitely costs less to deny teachers adequate non-contact time to reflect, prepare and re-charge their batteries in order to give good lessons.
Third, it is certainly cheaper to push older, more experienced teachers out of the profession, replacing them with new teachers who, with the best will in the world, cannot always produce good lessons.
Fourth, it is cheaper not to provide the adequate space and proper resources required to teach a good lesson in a good environment. Fifth, by making classes bigger it becomes unnecessary to spend money on more staff for an expanding subject.
Sixth, it is far, far cheaper to cut special needs support and, by means of a high-sounding code of practice, to pass the buck to the hapless classroom teacher, already overloaded with bureaucratic targets and associated paperwork.
As well as being untrue, Mrs Shephard's words were demoralising because the job satisfaction of giving bad lessons is minimal. It is not worth the loss of energy, free time and "quality of life". I am getting on, but I have colleagues half my age who finish the day worn out and, once home, go to bed.
I would be very surprised if a majority stay the course. We seem to be heading towards a profession with a high turnover of young staff regularly replaced by supply teachers.
TES readers may remember a letter published a few years ago telling the story of a German teacher on exchange who, after a few weeks, had to lower her own high standards, having collapsed in a supermarket.
After only a week our French exchange teacher announced that he would rather work down a mine! In France he had an average timetable, 16 lessons of 50 minutes each per week. He was replacing a teacher who had 25 lessons of 50 minutes a week plus 20 minutes of tutor time a day. "You have no time to think about your lessons properly," he said.
On reflection, we should perhaps be grateful to Mrs Shephard for her outrageous words. They so incensed me that I was driven to some serious thinking.
Maybe we should reproach the unions for aiming their fire too much at pay and not enough at funding or at class size. So - un grand merci, Gillian - or is it too late to learn?
The writer is a secondary teacher in London