One of the things I learned from @KentBeck years ago was to see cohesion in terms of divergent change rates. If you have a class and there's a set of methods that you tend to change together while leaving others alone, that set of methods could be a separate responsibility.

Once I saw this, I went so far as to write a script to mine classes in Git and find clusters of methods that all seemed to change at the same time.

Often the results were not surprising. You could've see new responsibilities emerging just by looking at the names of methods and variables. But, sometimes this time view of the code was the first indication that a class was trying to split.

Code isn’t special that way. This is all systems stuff. If you have a group of 10 people and 3 of them often change their minds together, you can start to see them as a separate group. They may even start to see themselves as a separate group. Why does this happen?

At its base, it’s because of the tension between N and N^2. As the number of things increases, the number of possible interconnections grows (bounded by N^2). It’s harder for 10 people to coordinate than 3, so we shouldn’t be surprised to see groups from cliques periodically..