I’d much rather eat a a cheesecake baked by a great cook than a Black Forest gateau baked by PhD-holder in cuisine. And I’d much rather read a missions book by a missionary than a missions book by a missiologist. Missiologists are often armchair missionaries. They write from a comfortable desk in their homeland.
I want the book to smell of dusty pathways and busy marketplaces, to sound like foreign voices, to taste of danger, sadness and joy. This is why great missionary biographies are the best books on missions. They’ve been there and done it.
There are exceptions, sure. Some great books on missions were not written by life-long missionaries (e.g. Paul the Missionary by Schnabel; Missionary Methods by Allen). But a main reason Clark’s work takes flight is because he’s labored on the mission field himself.