"It has now become the doctrine of a large clan of politicians that political honesty is unnecessary, slow, subversive of a man's interests, and incompatible with quick onward movement"

In this quote, author Anthony Trollope is expressing his belief that there is a group of political leaders who have adopted the idea that being honest in politics is not important. They see it as a hindrance, something that decreases progress and breaks their own individual gain. These political leaders focus on fast advancement and are willing to compromise honesty in order to achieve it. Trollope is criticizing this state of mind, recommending that it is dangerous and undermines the integrity of the political system. He is highlighting the value of sincerity in politics and the unfavorable effects that can develop when it is overlooked.