The old analogue way of searching for information was to go to a library, look in a catalogue and find a section of the shelves that contained a few book titles that might contain the information you want. If you did a metasearch you could search every word on every page in every book in the library. After that the library could link to other libraries to search every word on every page in every book in that library, and so on.
If ISP keep metadata for two years this would be sufficient for ASIO to use a search engine that would re-construct a persons life in minute detail from moment of birth by just typing in their name and date of birth. The thing about metasearch is that it is possibly to start with very limited information and every little bit of data leads to more data that leads to more data and so on ad-infinitum.
If the Abbott government gets the data retention laws through parliament your very soul will be laid bare to ASIO. You do not have to be a criminal or terrorist to fear this legislation. All you need is the desire to retain some areas of your life as private. If this legislation passes it will give the government the ability know more about you than you know, and the ability to control your life like never before.
The government is spinning this as being a inconsequential piece of legislation to aid ASIO protect us from terrorism, but the reality is that this proposed legislation is the Australian equivalent of the American Patriot Act. Does Australia need it?