Hi all

I came across a reference today in Buston's commentary on the Vimalaprabhā of the Kālacakratantra to the
chu skyar gyi sgru ma
or
kalahaṃsa-māyā

The referent to a water-fowl/gander/duck/swan/drake-illusion is not familiar to me. 

Mght someone know what this particular illusion is, and have some references?

Cheers
James

--
James Hartzell, PhD(2x)
Center for Mind/Brain Sciences (CIMeC)
The University of Trento, Italy
and
Center for Buddhist Studies
Columbia Universtiy, USA