How Scientists formulateTheories?

Below is the excerpt from Richard Feynman's Lecture in 1964. From below we can get to know how scientists develop their theories.

"In general we look for a new law by the following Process. First we guess it. Then we compute the consequences of the guess to see what would be implied if this law that we guessed is right.Then we compare the result of the computation to nature,with experiment or experience, compare it directly with observation, to see if it works. If it disagrees with experiment it is wrong. In that simple statement is the key to science.It doesn;t make any difference how beautiful your guess is.It doesn't make any difference how smart you are, who made the guess, or what his name is --if it disagrees with experiment it is wrong."