's famous _Tableau historique des progres de l'esprit
humain_,[208] written while he was in daily fear of death by the
guillotine, and so giving the most striking instance on record of the
invincibility of an idealist conviction under the hardest pressure of
facts.

The argument of Malthus is a product of the whole previous course of
speculation. The question of population had occupied the French
economists. The profound social evils of France gave the
starting-point of their speculations; and one of the gravest symptoms
had been the decay of population under the last years of Louis XIV.
Their great aim was to meet this evil by encouraging agriculture. It
could not escape the notice of the simplest observer that if you would
have more mouths you must provide more food, unless, as some pious
people assumed, that task might be left to Providence. Quesnay had
laid it down as one of his axioms that the statesman should aim at
providing sustenance before aiming simply at stimulating population.
It follows, according to Gulliver's famous maxim, that the man who
makes two blades of grass grow where one grew before deserves better
of his country than the 'whole race of politicians put together.'
Other writers, in developing this thesis, had dwelt upon the
elasticity of population. The elder Mirabeau, for example, published
his _Ami des hommes ou traite de la population_ in 1756. He observes
that, given the means of subsistence, men will multiply like rats in a
barn.[209] The great axiom, he says,[210] is 'la mesure de la
subsistance est celle de la population.' Cultivate your fields, and
you will raise men. Mirabeau replies to Hume's essay upon the
'Populousness of ancient nations' (1752), of which Wallace's first
treatise was a criticism. The problem discussed by Hume and Wallace
had been comparatively academical; but by Malthus's time the question
had taken a more practical shape. The sentimentalists denounced luxury
as leading to a decay of the population. Their prevailing doctrine is
embodied in Goldsmith's famous passage in the _Deserted Village_
(1770):

'Ill fares the land, to hastening ills a prey,
Where wealth accumulates and men decay.'

The poetical version only reflected the serious belief of Radical
politicians. Although, as we are now aware, the population was in fact
increasing rapidly, the belief prevailed among political writers that
it was actually declining. Trustworthy statistics did not exist. I