It means, mans progress (maybe) is mostly driven by his needs and greed for the material things in life.
Namely, most human language feature four skills, divided into productive skills and receptive skills.
- Productive skills: speaking and writing.
- Receptive skills: listening and reading.
For a long time, human languages only featured one productive skill, speaking, and one receptive skill, listening. Writing and reading would appear at a later time within the ancient cultures of Mesopotamia (who invented the cuneiform writing system) and ancient Egypt (who developed hieroglyphic and demotic writing systems). Even today, many human groups living in isolated and remote areas have not developed writing and reading, relying solely on speaking and listening and on oral tradition (passing down the history of the group from one generation to the next) for their communication needs.
<span>He was working as an engineer in Switzerland at the time.
"Was working" is past progressive. </span>
