No mystic ever saw deeper meaning in common things. The mystic sees the ineffable, and the psycho-pathologist the unspeakable. There is a singular fascination in watching the eagerness with which the learned author ferrets out every circumstance which may throw discredit on his hero. His heart warms to him when he can bring forward some example of cruelty or meanness, and he exults like an inquisitor at the auto da fe of an heretic when with some forgotten story he can confound the filial piety of the Rev. Robert Strickland. His industry has been amazing. Nothing has been too small to escape him, and you may be sure that if Charles Strickland left a laundry bill unpaid it will be given you in extenso, and if he forebore to return a borrowed half-crown no detail of the transaction will be omitted.

上面节选中： There is a singular fascination in watching the eagerness with which the learned author ferrets out every circumstance which may throw discredit on his hero.

这一句没看懂究竟是什么意思？尤其是in watching the eagerness + 后接定语从句， 这里watching the eagerness这是什么意思呢？

麻烦老师能分析一下句子成分和含义。