But where does it come from and what exactly does it mean?

It is the work of the French 18th century writer and philosopher Voltaire, and it appears

at the end of his legendary novel CANDIDE, written in just three very inspired days in

1759.

The clue to its meaning lies in the subtitle of this novel: CANDIDE - OR OPTIMISM.

Voltaire's goal in writing his book was to destroy the optimism of his times, an optimism

that centered around science, love, technical progress and reason. Voltaire was indignant.

Of course science wasn't going to improve the world; it would merely give new power

to tyrants. Of course philosophy would not be able to explain away the problem of evil;

it would only show up our vanity. Of course love was an illusion; humans irredeemably

wicked, and the future absurd. Of all this his readers were to be left in no doubt. Hope

was a disease and it was Voltaire's generous goal to try to cure us of it.

Nevertheless, Voltaire's novel is not simply a tragic tale. The book ends on a memorably

tender and stoic note. The hero Candide and his companions have travelled the world and

suffered immensely: they have known persecution, shipwrecks, rapes, earthquakes, smallpox,

starvation and torture. But they have – more or less – survived and, in the final pages,

they find themselves in Turkey – a country Voltaire especially admired – living in

a small farm in a suburb of Istanbul. One day they learn of trouble at the Ottoman court:

two Viziers and the Mufti have been strangled and several of their associates impaled. The

news causes upset and fear in many. But near their farm, Candide, together with his friends

Martin and Pangloss, pass an old man who is peacefully and indifferently sitting under

an orange bower next to his house. Let's listen to an extract:

Pangloss, who was as inquisitive as he was argumentative, asked the old man what the

name of the strangled Mufti was. 'I don't know,' answered the worthy man, 'and I

have never known the name of any Mufti, nor of any Vizier. I have no idea what you're

talking about; my general view is that people who meddle with politics usually meet a miserable

end, and indeed they deserve to. I never bother with what is going on in Constantinople; I

only worry about sending the fruits of the garden which I cultivate off to be sold there.'

Having said these words, he invited the strangers into his house; his two sons and two daughters

presented them with several sorts of sherbet, which they had made themselves, with kaimak

enriched with the candied-peel of citrons, with oranges, lemons, pine-apples, pistachio-nuts,

and Mocha coffee… – after which the two daughters of the honest Muslim perfumed the

strangers' beards. 'You must have a vast and magnificent estate,' said Candide to

the turk. 'I have only twenty acres,' replied the old man; 'I and my children

cultivate them; and our labour preserves us from three great evils: weariness, vice, and

want.' Candide, on his way home, reflected deeply on what the old man had said. 'This

honest Turk,' he said to Pangloss and Martin, 'seems to be in a far better place than

kings…. I also know,” said Candide, “that we must cultivate our garden.'

Voltaire, who liked to stir the prejudices of his largely Christian readers, especially

enjoyed giving the idea for the most important line in his book – and arguably the most

important adage in modern thought – to a Muslim, the true philosopher of the book known

only as 'the turk': Il faut cultiver notre jardin: 'we must cultivate our garden'

or as it has variously been translated, 'we must grow our vegetables', 'we must tend

to our lands' or 'we need to work our fields'.

What did Voltaire mean with his gardening advice? That we must keep a good distance

between ourselves and the world, because taking too close an interest in politics or public

opinion is a fast route to aggravation and danger. We should know well enough at this

point that humans are troublesome and will never achieve – at a state level – anything

like the degree of logic and goodness we would wish for. We should never tie our personal

moods to the condition of a whole nation or people in general; or we would need to weep

continuously. We need to live in our own small plots, not the heads of strangers. At the

same time, because our minds are haunted and prey to anxiety and despair, we need to keep

ourselves busy. We need a project. It shouldn't be too large or dependent on many. The project

should send us to sleep every night weary but satisfied. It could be bringing up a child,

writing a book, looking after a house, running a small shop or managing a little business.

Or, of course, tending to a few acres. Note Voltaire's geographical modesty. We should

give up on trying to cultivate the whole of humanity, we should give up on things at a

national or international scale. Take just a few acres and make those your focus. Take

a small orchard and grow lemons and apricots. Take some beds and grow asparagus and carrots.

Stop worrying yourself with humanity if you ever want peace of mind again. Who cares what's

happening in Constantinople or what's up with the grand Mufti. Live quietly like the

old turk, enjoying the sunshine in the orange bower next to your house. This is Voltaire's

stirring, ever-relevant form of horticultural quietism. We have been warned – and guided

How to think more effectively is a book about how to optimize our minds so that they can more regularly and generously produce the sort of insights and ideas we need to fulfill our potential and achieve the contentment we deserve.