On your favorite night before going to sleep, close your eyes in the dark and think of the largest possible mental space that can be perceived by your mind, outwards.
You will pleasantly discover that it is a void black sphere of radius R, with your consciousness at the very center. Think of any radius R you want. 25 light years, say. You can make your mind's radius larger than that: You can visit, say, Vega, mentally.
Think of another radius: 33,000 light years. That's roughly the distance to the center of the Milky Way. By mentally visiting this location, you can make your mind's radius larger than 30,000 light years.
Now think of some really large radius. 10^10^10^10 light years, say. This number will take you out of the known universe by zillions of orders. You can again make your mind's mental sphere radius greater than that, provided you can approximately perceive the immense size of this number, relative to unity.
For any radius R one gives you, you can expand your mind to a mental sphere of radius greater than R, provided you have sufficient understanding of the size of R.
Doesn't that imply that the mind is (potentially) infinite?