Who am I?
I am your constant companion. I am your greatest helper or heaviest burden. I will push you onward or drag you down to failure. I am completely at your command. Half the things you do, you might just as well turn over to me and I will be able to do them quickly and correctly.
I am easily managed, you must merely be firm with me. Show me exactly how you want something done and after a few lessons, I will do it automatically. I am the servant of all great men and women and alas of all failures as well. Those who are great, I have made great. Those who are failures, I have made failures.
I am not a machine, thou I work with all the precision of a machine, plus the intelligence of a human being. You may run me for profit or run me for ruin, it makes no difference to me.
Take me, train me, be firm with me and I will place the world at your feet. Be easy with me and I will destroy you.
Who am I?