A turn of mind
Definition 1 of 1
Pro Tip 1/3Cognitive Traits
It often describes a person's habitual thought patterns and intellectual inclinations more than mood or emotion. 
His scientific turn of mind made him a perfect candidate for the research team.
Pro Tip 2/3Personality Insight
A 'turn of mind' gives insight into someone's personality, especially how they approach problems or ideas. 
With her creative turn of mind, she often thinks outside the box.
Pro Tip 3/3Nuanced Understanding
Understanding the nuance can help deduce if the phrase is a compliment or a mere observation. 
His philosophical turn of mind isn't always practical, but it's interesting.