Final answer:
The quote in question was authored by Surrealist artist Rene Magritte. He is known for his dream-like surrealist paintings that challenge the conventional perceptions of reality.
Step-by-step explanation:
The author of the quote "We see it as being outside ourselves even though it is only a mental representation of it that we experience inside ourselves" is Rene Magritte. Magritte, a renowned Surrealist artist, was known for his thought-provoking, dream-like images and philosophical statements that challenged perceptions of reality. He had a significant influence on the arts, with profound implications on not only artists but various aspects of culture. The surrealist element of his work led to the creation of captivating paintings that address the relationship between objects, perception, and mental representations. Your question reflects the complex themes often found in Magritte's work, where what is seen is often a symbol or representation of deeper ideas.