An Essay on the Education and Instruction of Children. Sulzer commented on infant behaviour:
They see something they want but cannot have; they become angry, cry, and flail about. Or they are given something that does not please them; they fling it aside and begin to cry. These are dangerous faults that hinder their entire education and encourage undesirable qualities in children… The moment these flaws appear in a child, it is high time to resist this evil so that it does not become ingrained through habit and the children do not become thoroughly depraved.
Therefore, I advise all those whose concern is the education of children to make it their main occupation to drive out willfulness and wickedness and to persist until they have reached their goal.