Laziness is a sin, everyone knows that. We have probably all had lectures pointing out that laziness is immoral, that it is wasteful, and that lazy people will never amount to any thing in life. But laziness can be more harmful than that, and it is often caused by more complex reasons than simple wish to avoid work. Some people who appear to be lazy are suffering from much more serious problems. They may be so distrustful of their fellow workers that they are unable to join in any group task for fear of ridicule or fear of having their ideas stolen. These people who seem lazy may be paralyzed by a fear of failure that prevents fruitful work. Or other sorts of fantasies may prevent work; some people are so busy planning, sometimes planning great deals or fantastic achievements that they are unable to deal with whatever 'lesser' work is on hand. Still other people are not avoiding work; strictly speaking, they are merely procrastinating rescheduling their day. Laziness can actually be helpful. Like procrastinators(拖延者), some people may look lazy when they are really thinking planning, contemplating, researching. We should all re member that some great scientific discoveries occurred by chance or while someone was 'goofing off(游手好闲)'. Newton wasn't working in the orchard when the apple hit him and he devised the theory of gravity. All of us would like to have someone 'lazy' build the car or stove we buy, particularly if that 'laziness' were caused by the worker's taking time to check each step of his work and to do his job right. And sometimes, being 'lazy'--that is, taking time off for a rest --is good for a overworked student or executive. Taking a rest can be particularly helpful to the athlete who is trying too hard or the doctor who's simply working himself overtime too many evenings, at the clinic. So be careful when you're tempted to call someone lazy. That person may be thinking, resting, or planning his or her next book. The main idea of this passage is that ______.