Of the impulse to expression and what it meant in Boswell's case something has been said already in these pages. We cannot understand the engine if we forget the power that drives it, and we must emphasise once again the force that Boswell obeyed. His passion for truth was not comprehensive: and it was for the truth of the realist, not the truth of the idealist. It did not include the whole of life; it did not attempt to view the entire scene in correct perspective; and Boswell was decidedly not a philosopher. He did not greatly need explanations of the universe; he tended to accept such as seemed convenient. He had no logic about abstract theories, and only a very limited power of criticising evidence. One who cares for truth with respect to every fact and deduction is inclined to reject his first impressions, because experience has taught him that 'all men are liars.' The face of things is so often false! But Boswell was content to look no further; he sometimes deliberately disregarded the facts of existence; he lived one half his life in a glitter of his own creation. Nevertheless, the passion for truth was vivid and vital. It lived apart to work out its own consummation; and it was all the more vehement for being confined. It is perhaps for this reason--that the truth inherent in Boswell was confined within such strict limits--that it required expression. In these circumstances Boswell's buoyant nature had need of a safety-valve. Truth for him was concerned entirely with an external view of people. He was rarely analytical; he did not care for subtle states of mind and the feelings that composed them; he looked directly at actions and their primary motives. The vision was so clear and strong that Boswell by its very insistence was obliged to create an imperishable image. The reasons that made it certain from the beginning that Johnson would become the vehicle for this expression extend beyond those qualities which made Boswell prefer and admire him above all other men; they depend upon Boswell's attitude towards mankind. We have seen that he apologises and justifies himself for relating the weaknesses and absurdities of Johnson. And yet he sometimes seems to have a peculiar delight in them. These shades in Johnson's character are dealt with not as an unpleasant but necessary task, to be despatched with a light touch as though it ill became him to speak of them, but with a full flavour of rich and lasting enjoyment.