When we have a look at history of human, we find that in the past, there have been very limited occupations, jobs and professions in different societies such as ranching, agriculture and blacksmith. But today, because of human advancement in different fields and aspects of daily life, specially in science and technology, many careers and businesses have been created, and for satisfying the need of societies to these careers, societies need more workers.
On the other hand, due to the advancement of societies in the fields of technology and science, it's not possible for one, to get professional in more than one field. for example, science of medic was very limited in the past, so, a medic could learn other fields of science such as chemistry, physics, math, philosophy, and even literature and art, like Leonardo Da Vinci. But today, the science of medic, has advanced so that it has many variations, and getting professional in any of those variations, needs a lot of time and attempt.
Consider Leonardo Da Vinci, as a painter, inventor, medic, and scientist of the medieval era. If he wanted to live in today world, probably he only could learned anatomy and get professional in the field of anatomy, and there would not have remained any time for him to learn art,so we could not see his beautiful paintings.
On the other hand, due to the advancement of societies in the fields of technology and science, it's not possible for one, to get professional in more than one field. for example, science of medic was very limited in the past, so, a medic could learn other fields of science such as chemistry, physics, math, philosophy, and even literature and art, like Leonardo Da Vinci. But today, the science of medic, has advanced so that it has many variations, and getting professional in any of those variations, needs a lot of time and attempt.
Consider Leonardo Da Vinci, as a painter, inventor, medic, and scientist of the medieval era. If he wanted to live in today world, probably he only could learned anatomy and get professional in the field of anatomy, and there would not have remained any time for him to learn art,so we could not see his beautiful paintings.