Tallulah Bankhead had the healthiest attitude to hindsight. "If I had to live my life again," the hard-living American actress said, "I'd make all the same mistakes - only sooner." Regret, as we all know, is futile and disappointment as much a valid ingredient in anyone's make-up as success. On the other hand, as Ms Bankhead's deathbed words were reputedly "Codeine ... bourbon", perhaps we should acknowledge that even the most perceptive of observers could occasionally do with a spot of retrospection.
In that spirit, we asked half a dozen teachers to write letters to their younger selves (see pages 24-28). What career advice would they give, what knowledge would they share? Would they chastise immaturity, soothe under-confidence, praise foresight or berate themselves for too much time-wasting and not enough focus?
As you would expect, their experiences and advice vary. But despite their different career trajectories - indeed, different countries - there was a surprising degree of unanimity. What is immediately obvious is a shared love of teaching. Whatever the frustrations, none regrets choosing the profession. On the contrary, the overriding impression is that there is no more rewarding or worthwhile one.
What is equally apparent, however, is how challenging teaching is at first. Most admit to early difficulties: "You're petrified when you start"; "It gets better"; "The job gets easier with experience". Later success did not begin with blithely confident first steps.
The teachers found different ways to deal with pitfalls. "Don't judge yourself too harshly," one says, "mistakes will only make you stronger." "You will learn to cope with change even if you don't relish it," another says. Some are stoic: "Stick up for yourself without ranting or raving." Some are crafty: "Find successful ways to integrate your own passions into your teaching." Others are relentless: "Smile in every lesson." All probably came to this conclusion at some stage: "Although teaching is all-consuming, don't let it consume all your evenings and weekends."
A few wish that they had been more adventurous: "Don't play it safe"; "Don't turn down the chance to do something different". And they are split between those who have ranged widely across different regions and different types of schools and those who have stayed in the same area and even the same school for most of their careers.
Success is universally defined as student achievement, whether academic or vocational. And it is attained in a daily, incremental way. "Many of the striking things in your career will be the little things," one teacher notes.
Experience has become an undervalued commodity in education. It is an entirely good thing that so many motivated and well-qualified candidates are entering the profession. And it is refreshing that they are so keen to make their mark. But eagerness untempered by maturity and innovation unleavened by experience can be foolish.
Those tyro teachers in a hurry to make a difference could do worse than read our correspondents' advice. "Remember," one old hand counsels, "excellence in teaching comes one student at a time, one class at a time, one day at a time." Success is grind rather than grand.