His work is full of vigour.

The root of this tree is very deep and strong.

The roots of the plant are the source of its vitality.

Life is precious.

He is a strong person.

The source of this river is halfway up the mountain.

There are various types of plants in my garden.

Mr. Minamoto is my best friend.

What is the source of this information?

The fountainhead of this river is at the top of the mountain.