Laying is a transitive thing - you do it to something.
Lying is intransitive - you just do it.
e.g. " I was lying on the couch when I realised that my wife was laying lunch on the small table next...
Lying down is for a person: You are lying down. Laying down is for an object: You are laying the pen down There are many such verbs in English, where the transitive form of the verb may resemble the...