US-P18.169ab ।US-P18.169cd ॥
In plain words
The terms 'thou' and 'that' come to rest on the same referent, as 'blue' and 'horse' do in 'a blue horse'; through association with the word that declares freedom from sorrow, the word 'thou' reveals that meaning.
Close to the Sanskrit
Because 'thou' and 'sat' have the same referent, this would be like 'a blue horse'; through connection with a word denoting freedom from sorrow, the word 'thou' gains that reference.