Capítulo 13: I have a question

Sooo.... even if this will spoil the next chapter, I just don't wanna mess this up, I'll just say it. Is the first soul core mentioned in this pic(the pic is in the comments), the soul core formed when a spirit master reached spirit saint rank, or is it literally the first soul core a spirit master formed? It's been so long since I last read the original series, and my memory isn't that good so I maybe forgotten some important details in the original story, I cannot find the chapter that mentions the info of it. I need help lol, I can't finish the chapter because of this.