I don't believe anyone will be able to answer your question because its not specific enough. The word "proper" is too vague. I would place that "proper" time to around when early biologists began to discover cells, but this understanding would be different all over the world and different time periods.

There were all kinds of ideas but I Get the impression you are asking about humorism. This is the idea that a mixture of humors such as black bile, yellow bile, phlegm and blood was what made one healthy or ill. There was also an idea that everything was made of a combo of four elements. link