When doing contract design work, I am frequently required to learn a substantial amount about a new subject. Sometimes the material is personally interesting, but often it is not. As a point of professional pride I try to put equal effort into both sorts of information.
I've recently started reading the "Kingkiller" series of books, which currently includes only two volumes: The Name of the Wind and The Wise Man's Fear, Both are excellent. They broadly tell the story of Kvothe - a man who learned to be a wizard, a thief, a bard, a lawyer, a warrior, a doctor, a chef - essentially he's the most diverse multi-class character ever.
One of his chief skills for learning so much is a mental technique called "The Heart of Stone." It's a calming mental technique which pushes aside emotions and distractions - allowing a student to focus 100% of their mental energy on absorbing the material in front of them.
This technique jumped out at me because it's essentially the opposite of how I learn best.
Learning is a complex process, but at its core it is all about forming associations between different ideas. It's partially memorization, and partially about contextualization. Both of those processes are improved when you have a wide selection of ideas to associate against - clearing your mind seems, to me, to be entirely counter productive in hat pursuit.
I have a new member of my family, which means I have a new birthday to remember. Learning and remembering a new birthday is a process I take seriously. In this case, I remember the new birthday by thinking about how it falls in relationship to other birthdays - what it means for potential outdoor birthday parties - what it means for placement in school - what years might mark high school graduation and so forth. All of that takes place in a mind which is not empty - but rather full of information, opinions, and ideas.
Information in the world
This ties into a memory technique which I learned as "storing information in the world." The idea is that we do not need perfect recall of a topic in order to engage with it. We don't need to remember where every stop sign is along the road - because we can see them while driving. I don't need to remember every appointment I've made - because I have the recorded in my planner. I don't need to remember whether the yard debris goes out this weekend or next - because I've built up a habit of placing it on opposite sides of our garbage can to indicate whether this is yard debris week or not.
This is probably a familiar concept to most people under 40, because the rise of "search" and ready information through sites like Wikipedia has allowed more and more of our information to move "into the world" instead of keeping everything in our heads. In a world like ours, learning where and how to access information is much more useful than memorizing things by rote. Those are associations - the sort of learning that comes from being attentive, not from closing yourself off.