《明史·志·卷五十四》
经费不够支出，便命令臣民捐献资助；捐献资助不止，又实行与国外往来。
经费不敷，乃令臣民献助；献助不已，复行开纳。
When funds were exhausted, he ordered the nobles and commoners to donate money. When that was not enough, he started trading with foreign countries.