I am a final year math major thinking of taking Category Theory (CT). The problem is people keep telling me its useless. Why? I have a biology degree and decided to get a second degree in mathematics. My motivation for studying mathematics is related partly to an idea I stumbled across in high school and to my total love of biology. I recall realizing, at about 16, that scientific models are not always domain specific; that some are versatile. This idea had been swimming around in my head for years until I read a description of CT. And now I'm wandering whether there is a real equivalence between this "versatility" and CT So, does the equivalence exist? And why do people keep writing it off as "abstract nonsense". Can I use CT as a tool to build versatile "models"? Thanks!