There's method to my madness

Means doing something look strange but you have a plan and really, you doing something very sensible ( nôm na là có ý nghĩ điên rồ khi làm cái gì đó, làm cái này đúng nhưng chọn con đường ngược lại, ...)
Ex:
1. I'm driving to my friends house today but I'm going to take the long route, avoid the motorway. There's method to my madness. I think the motorway will be very busy and the long route will be quicker.
2. A: What are you doing putting all the books on the floor?
   B: There's method to my madness. I'm taking a photo of the books I'm putting away. The photos will help me locate the books more easily.
  A: Oh, that's clever.