careful and careless are as different as fire and water. but strangely, many scientists have both these qualities, that is, they are both careful and careless. newton, the well known english scientist, is such a person.

　　once newton invited a friend to dinner at home. when they were ready to eat, newton left to get a bottle of wine. but after his friend had waited for a long time, newton still didn't come back. finally his friend found newton in his lab. the reason was that when newton was going to get the bottle of wine, he suddenly had a new idea for the experiment he was doing, so he completely forgot his friend and the dinner. there was another time when newton was leading a horse up a mountain holding the rein in his hand. while he was walking, he kept thinking of problems he had met in his studies. when he got to the top of the mountain, he found that the rein was not in his hand and the horse was gone.

　　many scientists are careless about how they live. this is because they are too careful in their studies.