For me, the voice of conscience urges us to act with integrity - to be honest, straight and honourable in all our dealings and doings, whether or not anybody knows about it. The thing that matters is that we know we have done the right thing for the right reason. A more down to earth example is that of a blacksmith mending a cart:
"Always do the very best job you can," he said on another occasion, as he put a last few finishing touches with a file to the metal parts of a wagon tongue he was repairing.
"But that piece goes underneath," Garion said. "No one will ever see it."
"But I know it's there," Durnik said, still smoothing the metal. "If it isn't done as well as I can do it, I'll be ashamed every time I see this wagon go by - and I'll see the wagon every day."
So integrity may be defined as doing the right thing for the right reason. But there is more to it than that. I used to be a librarian, so the first thing I do when I want to find out what something means is to turn to a reference book, in this case The Concise Oxford Dictionary. The dictionary defines integrity as "wholeness, entirety, soundness, uprightness, honesty." It means adopting a whole heart and soul approach to our lives, so that we do not detract from our spiritual wholeness by any mean action or thought. This is a lot harder than it sounds - most people (and I would certainly include me in this) often fall short of this ideal, and compromise our standards of what we know to be right, falling into the gap between the talk and the walk.
I think that integrity means more than this, however. To me, the most important part of that definition is "wholeness." For example, you can talk about a machine or a building having 'structural integrity', which means that all the parts of it fit together in the right way and work together. Going back to people, it means striving towards the best we know, acting consistently according to what we believe is right, and not allowing ourselves to deviate from this standard. In this way, our whole selves, body, mind and soul, can have integrity and wholeness.
Acting with integrity also involves thinking for yourself. I love Abraham Lincoln's words: "I am not bound to win, but I am bound to be true. I am not bound to succeed, but I am bound to live up to the light I have." This implies making a judgement about what you think and believe to be right and true, and then sticking to it, no matter what anybody else thinks.
It is not an easy path, but the attempt has to be made.