ZYB SP talk, page-239

I certainly don't want to argue or in fact be a teacher (which I am not) But something is puzzling me... The money you invested , the original amount , was that profit from another trade? If so then the whole purchase is "free carried, or free money" so when does it stop being free money/carried investment??? SO the Free carried Zyber you hold, in the future if you sell, is all that free money, so when you invest in another stock say BHP to name one... are all your BHP shares free carried, or is the original purchase "your capital" and only any profit becomes free money again.. Your initial method I fully understand , but moving forward with subsequent investments needs some clarification