Notice of this anniversary and a discussion of Darwin's obsessive walking popped up this week in my online Literary Hub.

The piece by Jeremy DeSilva, titled On The Link Between Great Thinking and Obsessive Walking, rather leapt out at me (or perhaps one should say in this context, strode purposefully up to me) because I have been an obsessive walker all my life.

Quickly, I qualify that I have no tickets on myself as a great thinker and that it was the words "obsessive walking" that caught my attention. But all obsessive walkers will testify that walking, especially long, solitary walking, really does lubricate the mind and make for clearer, nimbler thought. DeSilva shows how important Darwin's obsessive regular-as-clockwork daily walks near his home were while he, Darwin, was compiling his groundbreaking Origin tome.

DeSilva points to others whose walking was an essential accompaniment of their genius.

"The 19th-century English poet William Wordsworth is said to have walked 180,000 miles in his life. On one of those walks he discovered his dancing daffodils. French philosopher Jean-Jacques Rousseau once said, 'There is something about walking which stimulates and enlivens my thoughts ... my body has to be on the move to set my mind going'."

I am no Darwin or Rousseau but I love to walk. And so I confide that on my long walks (these days usually in the whispering forests of Canberra's National Arboretum) my mind Darwinially cleared and primed by this exercise, one of the issues I wrestle with at the moment is why my prime minister seems to be such a liar.

His struggles with the truth are famous now. The vicious (yet somehow fair) epithet "The Liar from the Shire" (for he is big on being a typical bloke of the Sutherland Shire) seems set to cling to him for eternity.

This very week the subject of what I will call (for it is sometimes necessary to invent words to fill essential vacancies in our language's vocabulary) his pinocchioism* dominated one parliamentary Question Time and seemed to be on everyone's lips whenever one tuned a device to news and current affairs.

One intellectually stimulating explanation of his pinocchiocity comes from Morrison biographer Sean Kelly. He diagnoses in his new book, The Game: A Portrait of Scott Morrison, that Morrison has a habit of saying one thing when it politically suits him and then, later, of saying its complete opposite when he thinks it politically suits him to say that opposite thing.

He's able to do this, Kelly said on ABC Radio National last Saturday, because he, Morrison, "has that ability to completely inhabit a moment ... of completely blotting out both past and future ... and this means he thinks he can say whatever he needs politically [in that moment] to say".

So, for example, it comes to pass that on the eve of the 2019 federal election Morrison roundly denounced electric vehicles but in recent days has not only sung their praises but has denied (with the watching, gasping, 2019-remembering world expecting his pants to spontaneously combust) that he ever said anything critical of electric vehicles. But he did. News footage captured it for eternity. How prime-ministerially raw this raw prawn he is coming!

Kelly's diagnosis is thought-stoking but is he correct in calling what Morrison does an "ability"? That word suggests a skill, an accomplishment, when some of us might think a human life lived for the animal moment, without thought for the past or the future, seems more of a disability. Perhaps it is something for which a sufferer should seek professional help.

No, there's no Machiavellian cunning in Morrison's so-called lies. If these utterances were truly, creatively cunning there might be some make-believe flair about them instead of their being the clodhopping, foot-in-mouth truth-manglers (like the EV mangles) his mangles always are.