Is There Really an Outer Mental Sense-Object?

Outer mental sense-objects, for example, are like the mountains outside; the shape of a mountain—its height, loftiness, grandeur, and so on—are all outer mental sense-objects. After the tathāgatagarbha makes contact with them, they are transmitted into the supreme faculty and become inner mental sense-objects, which the six consciousnesses can then discern.

If there were no outer mental sense-objects, and the mountains outside had only color with nothing else, then how could one distinguish this mountain from that mountain, or distinguish mountains, rivers, and the great earth? Surely the material universe could not just be a riot of colors and nothing more?

Person A is a person, and person B is a person. To B, A is an outer sense-object, including all six sense-objects of form, sound, smell, taste, touch, and dharma. A's height, build, gender, temperament, age, appearance, and so on are all outer mental sense-objects. After B's tathāgatagarbha makes contact with them, they are transmitted into B's supreme faculty and become inner mental sense-objects. One cannot say that A is merely a patch of colored form-sense-object, without outer mental sense-objects such as height, build, age, appearance, and so on. If every person were only a patch of color without mental sense-objects, then what difference would there be between any two people? Does each person's tathāgatagarbha use another person's tathāgatagarbha to create inner mental sense-objects? Does each person's tathāgatagarbha arbitrarily and randomly fabricate the appearance of another person's mental sense-objects?