The tetractys is a five-lined verse form invented by Ray Stebbings.   Its challenge is to express a complete thought within the narrow compass of twenty syllables.   The five lines contain the following syllable count: 1, 2, 3, 4, 10.   Multiple stanzas are allowed, but the series is reversed and alternated from one stanza to the next.

"Euclid, the mathematician of classical times, considered the number series 1, 2, 3, 4 to have mystical significance because its sum is 10, so he dignified it with a name of its own — tetractys.” — Ray Stebbings

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A Tetractys Verse
by Roger Robison

One
Complete
Thought is formed
In just five lines
With a total of twenty syllables.

Reverse the series to add a stanza,
Counting downward,
One per line,
Till there's
One.