Dear Jo, you ask which non-dispositional properties I am keen to preserve. I take the fact that I am a living being, with a certain size, shape and weight to be such properties. And my consciousness also seems a fairly fundamental property of me. Or do you take life just to be the disposition to breathe, ingest noursihment etc, consciousness no more than the disposition to sense and think?  I am no physicist, but I take the charge of a particle, and its spin, to be non-dispositional. I am glad to hear that you like what Berkeley wrote. As my favorite, Hume, said, his arguments admit of no answer, but produce no conviction. This thread began with claims about vision, and I take both my eyes and my brain to have a shape, a chemical composition, etc, which explains what they do, the dispositions they display, as long as they are part of a living being. Surely the cells you examined had some nature which explained their dispositional properties. Best wishes, Annette Baier.