It is a labor to task the faculties of a man ? such problems of profit and loss , of interest , of tare and tret , and gauging of all kinds in it , as demand a universal knowledge 这真是一个辛苦的劳役，考验着一个人的全部官能， ? ?这些赢利或损失的问题，利息的问题，扣除皮重的计算问题，一切都要确实数字，非得有全宇宙的知识不可啊。
