What make a programming language popular?

Recently there were many posts on programming languages (for eg. see excellent posts by Steve Yegge and Mike Vanier). That made me wonder what makes a programming language popular. Popularity seems to have no relation with the quality. Does a language become popular out of luck (or its name)? Or is there something else to it. The following is my take on what make a language popular:

1. Popularity
The main factor that makes something popular is popularity itself. The statement may appear circular, but like recursive functions it is valid. When you decided to learn a new language what did you do? You would've read reviews, blogs etc. The more reviews you read the better. And if you are constrained by your employer this is doubly true. I agree that nerds don't care about popularity. But nerds aren't so common.

2. Ease of Learning
The next factor is ease of learning. This is the first thing if you leave aside popularity. Btw, this may not mean the same as intuitiveness.
Let's say you have the option to learn C++ and Python. What would you choose? (Assume that you are not worried about other factors like performance etc)

3. Ease of Reading
Interestingly ease of reading and ease of learning are not the same. For example, Perl is easy to learn (at least to get started), but exceedingly difficult to read (especially large code-bases). Some languages become popular because of the learning factor but over time lose popularity because reading (and hence maintaining) code is difficult. So this is the first major factor that determines the long term popularity of a language.

4. Terse
Smaller code means easier maintenance. The ability of easily creating abstractions (using closures, macros etc) is the main factor here. But then Lisp should be more popular than java right? But remember, this is the 4th factor. And java excels in all the above factors (maybe due to the way computer science is being taught). And many people think that if it tries to add these 'advanced' features it'll become dead. It is unfortunate that the main factor that has to be considered in choosing a language - the level of abstraction it provides - is ignored. But then as Russel said: If fifty million people say a foolish thing, it's still a foolish thing.