He is perhaps the most famous bear in literature and now, on Winnie-the-Pooh's 90th birthday, one academic believes the "Poohisms" uttered in AA Milne's classic children's books are life lessons that rival the wisdom of the greatest Greek philosophers.

When Winnie-the-Pooh - based on the author's son Christopher Robin and his stuffed toys - was first published in 1926 it was an immediate success, selling 35,000 copies in Britain and 150,000 in the US.

Pooh fascination endures to this day, and Catherine McCall believes part of the allure of the thoughtful little bear is that the stories pose life's big questions in a way children can understand simply.

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Dr McCall, a patron of the Philosophy Foundation, said: "What I see in Pooh is really something just the same as the ancient Greek philosophers Plato and Aristotle, which is 'how to live a good life'.

"That is really what philosophy started being about and has been about for most of 2,000 years.

"Pooh addresses the same thing, but the way that the Poohisms are, they are a lot more accessible than reading ancient philosophers.

"Somehow AA Milne really managed to encapsulate the thoughts of great philosophers in really simple, direct language that people can access and understand."

Dr McCall believes the language given by Milne to his characters allow children and adults to explore complex ideas as they are reading.

She said: "There's one (Poohism) I think is absolutely amazing, and it's so simple: 'People say nothing is impossible, but I do nothing every day'.

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"As soon as you hear that you think about what 'nothing' means, because there are four or five meanings of 'nothing' in that little sentence, and you're thinking, 'what does impossible mean', and 'what does nothing is impossible' mean. Immediately you are thinking philosophically, whatever age you are."

Dr McCall believes the 2,000-year-old ideas explored in Pooh are still vital today.

She said: "I think they will always be relevant to human beings as long as we are human, because they are deeply to do with the human condition.

"Every generation needs to discover for itself how to live the good life. We think that things like technology and modern items change life dramatically, but the really important things about being human don't really change."

Such is the enduring love for Winnie-the-Pooh that it was recently named the UK's favourite children's book of the past 150 years.

A new book, The Best Bear In All The World, was released earlier this month to mark the 90th anniversary.

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One of its four authors, Brian Sibley, said the original books were still appealing because of Milne's "brilliant dialogue", which he said was "crisp and sharp and sparkles with wit".

He said the books work on multiple levels, with children able to enjoy the simple plots and be rewarded by understanding what is happening far before the character themselves do.

But adults can appreciate them because the characters reflect real life.

He said: "That's the brilliance of Milne as a playwright and dramatist in that what you get is characters that we all identify with - in our office, in our family.

"Wherever we are we all tend to know somebody who tends to be on the gloomy side like Eeyore, or a bit slow on the uptake like Pooh, or a bit nervous like Piglet, or bossy like Rabbit."

Mr Sibley said the tales were "timeless", constructed in a world entirely reliant on itself and uncluttered by outside influence, similar to the worlds of Peter Pan or Wind In The Willows.

He said the stories help readers understand their own place in the world and tolerate other people who are not the same as them.

To mark 90 years of Pooh, Disney has created a "Thotful Spot" bench that will tour the UK, complete with a talking Winnie-the-Pooh statue that voices the bear's top life lessons.