Why are eyes open in Zazen?

[Aloka]

Soto Zen teacher Brad Warner answers a question:

[Esho]

We keep eyes open to keep alertness while concentrated and during observation of thoughts and breathing.

[philg]

I do a lot of visualisation meditation, so I usually meditate with eyes closed.

[Aloka]

I meditate with eyes open, as taught by a Tibetan Buddhist teacher at Samatha meditation classes a number of years ago and followed by a Mahamudra meditation course (also with eyes open) given by another Tibetan teacher at a later date.

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[JadeRabbit]

I used to meditate with eyes closed, but found I would drop off to sleep or daydream in the evenings, after a days work. Since practicing Zazen with eyes half closed, I have found it much easier to focus and stay alert.

I also like Brad's mention of letting go of 'self' - closed eyes made me feel like thinking or 'self' existed behind my eyeballs, whereas that seemed to lessen with the eyes open.