Fionn's Window, sometimes referred to as Fionn's Shield, is named after the Irish hero Fionn Mac Cumhaill, who was a warrior chieftain and druid.
This 'window' is a diagram that can be marked on the ground and used for divining your journey, just like the 'I Ching'.
This series of rings represent the spine of each aicme, with the 5 characters from each aicme marked along north, east, south and west, and the 5 forfreda characters placed around the rings. By throwing a handful of sticks outward from yourself, starting at north and repeating in the other directions, you can see where the sticks land, and which of the characters are important to you at that time.
By using Fionn's Window it can provide you an insight to your inner self and an observational view on your place within the universe.
In Writer's Square, this observational viewpoint will be at the top of the steps looking along with Tree Alphabet to the Ogham Wheel.