About impermanent things we certainly know well. In fact whatever we know well are all impermanent things! Though what is permanent transcends the mind and speech, the shAstras do tell us about it.
It is from them that we learn the fundamental information about the eternal Atman. Dwelling in thoughts of That which can give permanent peace and permanent happiness, we should be able to throw off the the impermanent things which can give only impermanent peace and happiness.
It is not necessary to throw them off right in this beginning stage. Though they are not the permanent entity, Atman, there are several things among the impermanent ones that can help us go towards that permanent one.
The shAstras about the Atman, the teachings of great men about it, the holy pilgrimage centres that produce a pure state of mind, puranas and stotras and several similar ones, are all there. Of course none of these is the Atman.
However, all these can lead us to a close proximity to that. Thus there are things of happiness – what we then consider to be happiness – that range all the way from those which takes us to that Permanent experience to those which takes us away very far.