Since no amount of labour can produce an ounce of food-stuff beyond
the maximum producible by a limited number of plants, under the most
favourable circumstances in regard to those conditions which are not
affected by labour, it follows that, if the number of men to be fed
increases indefinitely, a time must come when some will have to starve.
That is the essence of the so-called Malthusian doctrine; and it is a
truth which, to my mind, is as plain as the general proposition that a
quantity which constantly increases will, some time or other, exceed any
greater quantity the amount of which is fixed.