How important are "good teachers" for a "good education?"

How true is it that "no education system is better than the quality of individual teachers?"

The opening paragraph in The Economist makes it clear what that newspaper thinks:

BUDGET, curriculum, class size—none has a greater effect on a student than his or her teacher. Given this, politicians might be expected to do all in their power to ensure that America’s teachers are good ones. For decades, they have done the opposite. The trouble begins long before a teacher enters the classroom. In Singapore, which recently came second in an international ranking of 15-year-olds’ skill in maths (America was 31st), the teacher-training programme accepts only students in the top 30% of their academic cohort. In America, most teachers were mediocre students. Only 23% of new teachers were in the top third of college graduates.

So, having quality teachers is the key, right?
I am not so sure.  (editor: could it be because you feel threatened that it will soon be revealed that you are a lousy teacher?  Awshutup!)

I am a lot more inclined to agree with the writer at Spiked who argues that education systems are increasingly messed up because of "the denigration of the idea of knowledge as an end in itself." There has been a systematic erosion of this notion that education is all about knowledge as an end to itself.  (One can immediately see how, therefore, a testing-centered No-Child-Left_Behind is messed up!)

When I was at school, academic knowledge was more valued than it is today; there was a far stronger belief in the value of education for its own sake. This was the principal central organising principle for educationalists, and it brought parents, teachers and educational elites together in a common endeavour.
In this climate, teachers could actually get on with teaching their specific subjects. There was undoubtedly a wide disparity in the amount of enthusiasm, talent, skill and success with which any individual teacher went about his or her work. And, like most people, I can remember teachers who were inspirational and others who were deathly dull. But the net effect was that school felt like a collective effort where pupils and teachers pursued a common goal. The sum was greater than its parts. So the education system was, and can still be, better than ‘the quality of its individual teachers’.
To look upon teachers as being solely responsible for the quality of education is both incorrect and unhelpful.

Yep, my story as well.  It seems like I had as many awful teachers as there were fantastic teachers.  But, even the awful ones made it abundantly clear that we were in school to learn and appreciate the wonders of knowing.  But, that does not seem to be the case anymore.  Why so?

the most disastrous has been the loss of faith in the pursuit of Truth, without which education starts to lack a point. 

Indeed!  I tell students that we pursue the truth--not there there is a magical book that reveals the truth. But, I am not sure even if university faculty convey and practice this message anymore.  Most of us merely Bullshit.  But, I digress.
I liked the following paragraphs even better than the first few:

We do need to accept that not all pupils will understand all subjects at school. While the government’s aim to help children ‘achieve much more than they may ever have imagined’ is laudable, this outlook is often mixed up with the idea that every child should achieve the same results. The idea that education should somehow create wider social equality is erroneous. Social equality is a complex political issue that can only be solved in adult society, not in schools.
The idea that education determines all later life chances is now widespread. Within the education system it has encouraged a focus on the assessment of common skills in order to allow for the most superficial kind of equality of outcomes.
However sincere the wish, education cannot, and should not, be thought of as ‘an engine for social mobility’. Past attempts to burden education with this task have failed and it has led to a degraded view of the value of knowledge, the consequences of which the Lib-Con coalition seems to underestimate.
Having a good education does not guarantee a comfortable adult life, with a nice house and an interesting, well-paid job. Social and material inequalities are neither entirely created, nor remediable, in the sphere of education. In fact, the paradox of education is that it is likely to be of greatest benefit when we afford it the greatest autonomy and insulation from the concerns of wider society.