An interesting text on Elvish dexterity from the Eldarin Hands, Fingers & Numerals.
This sentence was presented and analysed by Patrick H. Wynne under the title The Ambidexters Sentence in Vinyar Tengwar 49, attached to the essay Eldarin Hands, Fingers & Numerals. Tolkien composed it 1969 and there are seven successive versions, of which the version presented here is the final one.
The translation as provided by Tolkien:
The Elves were ambidexters;
consequently the left hand was not to them evil in their imaginations.
On the contrary. For if one turned the face westwards as was usual,
the left hand pointed away from Melkor,
and if northwards, it pointed towards Aman.