《资治通鉴·梁纪·梁纪五》
于是我就极力用自己的愚钝的头脑，钻研了很长时间，颇有收获。
遂竭愚思，钻研甚久，颇有所得。
"And so I applied my own thick head with great effort, and studied it for a very long time, with quite a few results; what is called correcting the pitch with the tuning standard is just a matter of using the tuning standard to adjust the musical instruments."