> Reportedly, Geoffrey Hinton said: “To deal with a 14-dimensional space, visualize a 3-D space and say 'fourteen' to yourself very loudly. Everyone does it.”

He did. You can see / hear that line in this video from his old Coursera course.

https://youtu.be/TNhgCkYDc8M?list=PLLssT5z_DsK_gyrQ_biidwvPY...

Exactly how seriously he intended this to be taken is a matter of debate, but he definitely said it.