I next condensed these into six taxonomic classes and reread all the letters carefully, placing each into one or more of the six (for a total of 163).

• 然后，我将这两打左右的类别归并成六个大类，再仔细重读每一封信，将每一封信归入一个（或几个）大类。结果这六大类中共有163封信。