An excerpt from a 1996 interview with Japanese voice actress Megumi Hayashibara (林原 めぐみ) who voices the characters of Rei Ayanami and Yui Ikari in the anime Neon Genesis Evangelion. I found this in NEON GENESIS EVANGELION 3-in-1 Edition Volume 1 published by Viz Media
"Expression isn't emotion. Emotions, rather, are sometimes something hidden deep inside the heart. The mind may not even be aware of them; and also, the mind may not even want to know. The subconscious has something deeper beneath it - these emotions float on a dark pool that rises up to try and drown them. It's your innermost conspiracy; the way you keep yourself ignorant of yourself."
More info about Megumi: https://en.wikipedia.org/wiki/Megumi_Hayashibara