She occasionally stopped and rushed off to ‘put some irons on the fire’, evidently getting excited over the project and putting her all into it. He chuckled – he didn’t understand cutie marks, but he knew enough that a pony’s cutie mark had something to do with their special talent, what they truly excel at. Blacksmithing was apparently Heat Source’s passion. He considered the implications of that, wondering what would happen if a pony grew up dreaming of becoming an astronaut to such an extent that it was all he or she thought of, only to get a cutie mark of a filing cabinet.