Frank J. Wilstach, comp. A Dictionary of Similes. 1916.

Serene

Serene and ephemeral as a little smiling sun.
—Anonymous

Serene as a star in a bright mist.
—Honoré de Balzac

Serene, like a deep, smooth, and still lake.
—Buddha

Serene as night.
—Lord Byron

Serene … like envoys from the skies.
—Nathaniel Cotton

Serene and calm, as when the Spring
The new-created world began.
—John Dryden

Serene as the dawn.
—Victor Hugo

More serene than Cordelia’s countenance.
—John Keats

Serene as summer in Arcadian hills.
—Charles L. Moore

Serene as a Quaker’s meeting.
—James Ralph

Serene as a winter sunset.
—Bernardin de Saint-Pierre

Serene, as in armour of faith.
—Margaret E. Sangster

Serene and pleased a look as Patience ere put on.
—James Thomson

Serene as light.
—Isaac Watts

Serene as day.
—William Wordsworth