Unlike Galton, Binet did not search for any single or 'theoretically basic' measure of intelligence. Instead, he tested items from all areas and kept any which worked.
Intelligence increases through childhood.
This rise occurs without any unusual sensory acuity or any special education or training. Used tests for which all subjects could be expected to have the required experience, avoiding tasks resembling schoolwork. We give him nothing to read, nothing to write, and submit him to no test in which he might succeed by means of rote learning. Used tests of abstract reasoning. 1905 Binet-Simon test of intelligence.