Language Point 58

The unconscious is certainly the source of instinctive activity. (Para. 7)
source: n. a place from which sth. comes or is acquired
The source of water for our watering network is the river near our farm.

我们灌溉系统的水源是农场附近的那条河。
The farms in the country are the source of food for the cities.

乡村农场是城市所需食品的来源。