Firewns said: is there anyone who can elaborate on why viriya types contemplate better on anicca, saddha types on dukkha, and panna types on anatta?
I will try to explain the best I can, based on my understanding.
Anicca is the inability to maintain something the way one wants it to be / or the way he likes it. A viriya type person is someone who will put a lot of time and effort in doing stuff, whether it is studies, work, family life etc. All this effort he puts in is to attain some kind of happiness or to maintain the way he likes it to be. Anicca basically means that whatever effort one might put into maintaining or achieving something, it will never be the way he likes it to be. So a viriya type person will contemplate on the effort he is putting to achieve something (mundane things) and will be easier for him to realise the worthlessness of that effort because everything is anicca.
Anatta, the way I understand it, is the fact that everything is in the end of no substance / value etc. A panna type person will be someone who will try to come up with the shortest or easiest way of doing things. His level of understanding will be higher, so he will not put as much effort as say a viriya person. So when this type of person realises that everything is anatta he realises that anything he does is, in the end, worthless.
Part of the Dukka that the Buddha is referring to is the dukka that one can get in the lower realms. To really see this dukka one needs to have faith in what the Buddha has said (unless one can develop abinna powers or samadi powers to see those things for himself). I find it hard to explain the connection between dukka and saddha here. I have a weaker saddha indriya and this may be a reason too.
But saying this, all three are connected. And I don’t think one should just stick to one type of contemplation. There are also, I think, nearly 30 types of sanna that one can use. Anicca sanna, dukka, sanna and anatta sanna are just three of them.