Strickland chuckled. He did not seem discouraged. He was independent of the opinion of his fellows.

And it was just that which had most disconcerted me in my dealings with him. When people say they do not care what others think of them, for the most part they deceive themselves. 

请教老师，句式it was just that which had most disconcerted...这是定语从句，还是强调句？ 这种句式怎么翻译呢？