Three matchbox cars are traveling at different speeds and directions: one at 10 m/s northeast, one at 10 m/s southeast, and one at 15 m/s northeast. This describes a vector space of possible matchbox car velocities. Properties of boxes that output consistent results like color or hardness can also be thought of as vector spaces, with inputs and outputs forming a basis. The key property is that the results are repeatable, like an electron always exiting a color box through the same aperture.