Nice comparison of Hoare vs. Dijkstra.
Hoare was more focused and diplomatic while Dijkstra was more of a free-ranging philosopher.
I still remember the first time i came across Hoare Logic/Triple and Dijkstra's GCL/Weakest precondition, understanding nothing and feeling like a complete dolt.
As a young'un i thought knowing the syntax of a language and learning some idioms/patterns was all you needed for programming. Reading Hoare/Dijkstra showed me where mathematical theory met programming practice.