What is without form is the mind. As for that [mind], the past mind has [already] ceased and perished. The future mind has not [yet] arisen or originated. As for the present mind, it is also difficult to examine: It has no colour and is without any shape. Since it is just like space, it is not established. Or, when analysed and scrutinised with the weapon of reasoning, it is free from unity and multiplicity. In other words, it is unarisen. Or, [it may be said that] it is natural luminosity and so on. Therefore, one realises that it is not established.

-- Atiśha