If we treat the general aptitude (or 'cleverness') of the children as differing only by more or less, the problem becomes one of fitting the types of school to a fairly exactly ascertainable polygon of intellectual variation.

It might appear then that the best results would come from the provision, say, of five types of schools providing respectively for the 2 per cent, of greatest natural cleverness, the succeeding 10 per cent., the intermediate 76 per cent., the comparatively sub-normal 10 per cent., and the 2 per cent, of 'mentally deficient.' That is to say the local authority would have to provide in that proportion Secondary, Higher Grade, Ordinary, Sub-Normal, and Mentally Deficient schools.
A general improvement in nutrition and other home circumstances might tend to 'steepen' the polygon of variation, i.e.to bring more children near the normal, or it might increase the number of children with exceptional inherited cleverness who were able to reveal that fact, and so 'flatten' it; and either case might make a change desirable in the best proportion between the types of schools or even in the number of the types.
It would be more difficult to induce a committee of politicians to agree on the plotting of curves, representing the social advantage to be obtained by the successive increments of satisfaction in an urban industrial population of those needs which are indicated by the terms Socialism and Individualism.

They could, however, be brought to admit that the discovery of curves for that purpose is a matter of observation and inquiry, and that the best possible distribution of social duties between the individual and the state would cut both at some point or other.

For many Socialists and Individualists the mere attempt to think in such a way of their problem would be an extremely valuable exercise.
If a Socialist and an Individualist were required even to ask themselves the question, 'How much Socialism'?
or 'How much Individualism'?
a basis of real discussion would be arrived at--even in the impossible case that one should answer, 'All Individualism and no Socialism,' and the other, 'All Socialism and no Individualism.' The fact, of course, that each step towards either Socialism or Individualism changes the character of the other elements in the problem, or the fact that an invention like printing, or representative government, or Civil Service examinations, or the Utilitarian philosophy, may make it possible to provide greatly increased satisfaction both to Socialist and Individualist desires, complicates the question, but does not alter its quantitative character.

The essential point is that in every case in which a political thinker is able to adopt what Professor Marshall calls the quantitative method of reasoning, his vocabulary and method, instead of constantly suggesting a false simplicity, warn him that every individual instance with which he deals is different from any other, that any effect is a function of many variable causes, and, therefore, that no estimate of the result of any act can be accurate unless all its conditions and their relative importance are taken into account.
But how far are such quantitative methods possible when a statesman is dealing, neither with an obviously quantitative problem, like the building of halls or schools, nor with an attempt to give quantitative meaning to abstract terms like Socialism or Individualism, but with the enormous complexity of responsible legislation?
In approaching this question we shall be helped if we keep before us a description of the way in which some one statesman has, in fact, thought of a great constitutional problem.
Take, for instance, the indications which Mr.Morley gives of the thinking done by Gladstone on Home Rule during the autumn and winter of 1885-86.