*self explanatory*, non-disposable knowledge! -bad or good etchings, (present, past, or possibly future...) on the malleable human mind. these could include: death/s, birth/s, divorce/s, non-disposable interaction of quality with other humans, assorted tragedy/s, etc...
these are the memories which we will carry to the grave!, (-like the time you got fucked so vigorously you wanted to cry for your mama!, but it still was glorious!!)

When you eat dirt for the first time and leave your family to build a shack in the woods