Sentence:  ... the <WSD>asswagement</WSD> of his discontent consists in two things, formerly prescribed as remedies against corporeall pain; "viz." Diversion of his thoughts from his losse, or the cause of it, and an application of them to those things, which he knowes to be gratefull and pleasant to his mind. 
Meaning of the word marked with <WSD> tags:  The action of assuaging; appeasement.