の根源

the root of

→ の
phrase Rare #38,607
the root of Indicates the fundamental source, origin, or cause of something. 根源 is a formal word often translated as “source,” “origin,” or “root.”
JA: 好奇心は学びの根源だ。
EN: Curiosity is the root of learning.

忍耐力科学の根源である

Perseverance is the foundation of science.

を嫌うのは言うまでもなく人を信頼できないことが人間の苦しみの根源

Needless to say, the root of human suffering is not being able to trust others.

これこそラピュタの力の根源なのだ

This is the very source of Laputa’s power.

— 天空の城ラピュタ (1986)