Beyond your ken
Definition 1 of 1
Pro Tip 1/3Not Literal
Understand it's figurative, meaning limited understanding, not actual physical distance or visibility. 
The reasons for his decision were beyond my ken.
Pro Tip 2/3Rarely Used
Know it's not common in everyday conversation, but found in literature or formal contexts. 
Her mastery of the subject was beyond my ken.
Pro Tip 3/3Intangible Concepts
Used for abstract ideas or complex topics, not simple, concrete items. 
The philosopher’s theories are beyond my ken.