(1) Society is human action - and in this sense all analysis is therefore micro-analysis.  (2) The second idea states that social systems are aggregates - and as such follow laws that cannot be derived directly from the individual act.  An aggregate is like a swarm of mosquitoes - the swarm consists of individual insects, and the motion of each insect varies considerably.  The motion of the swarm as a whole, however, is the product of all these individual movements, and as such may be described without reference to them.