Whilst Lotze had thus in his published works closed the circle of his thought, beginning with a conception metaphysically gained, proceeding to an exhaustive contemplation of things in the light it afforded, and ending with the stronger conviction of its truth which observation, experience, and life could.
Such are the four points of Cartesian method: (1) Truth requires a clear and distinct conception of its object, excluding all doubt; (2) the objects of knowledge naturally fall into series or groups; (3) in these groups investigation must begin with a simple and indecomposable element, and pass from it to the more complex and relative elements; (4) an exhaustive and immediate grasp of the relations and interconnexion of these elements is necessary for knowledge in the fullest sense of that word.4 " There is no question," he says in anticipation of Locke and Kant, " more important to solve than that of knowing what human knowledge is and how far it extends."
Before proposing the reintroduction of the tax, Sella and his friend Ferrara improved and made exhaustive experiments with the meter.
On his own initiative he conducted exhaustive inquiries into the conditions of the Sicilian peasants and of the Tuscan metayers, and in 1877 published in co-operation with Signor Leopoldo Franchetti a masterly work on Sicily (La Sicilia, Florence, 1877).
In order to 'ascertain what modes of action are most conducive to the end in view, and what motives are best fitted to produce them, Bentham was led to construct marvellously exhaustive, though somewhat mechanical, tables of motives.