One single grateful thought towards heaven, is the most perfect prayer!

[Ein einziger dankbarer Gedanke gen Himmel ist das vollkommenste Gebet!]

Gotthold Lessing (1729-1781) German playwright, philosopher, dramaturg, writer

Minna von Barnhelm, Act 2, sc. 7 [Minna] (1763) [tr. Holroyd/Bell (1888)]
    (Source)

(Source (German)). Alternate translation:

A single grateful thought toward heaven is the most perfect prayer.
[Source (1884)]