Galileo was quite controversial in his time because he was claiming that something we all could see with our own eyes wasn't true. We all could see that the Earth doesn't move, and that the sun, moon, and stars go around the Earth. This belief had been held for about 2000 years, and Galileo was saying that our eyes were deceiving us. He proposed that the Earth actually moves and is not the center of the universe. This challenged our common sense and deeply ingrained perceptions. For this assertion, he faced significant backlash and was even put under house arrest. It's human nature not to like being told that our senses might be misleading us.

But Galileo went further. He suggested that not only were our senses deceiving us about the movement of the Earth, but he also believed that tastes, odors, colors, and other sensory experiences resided within consciousness. He argued that if a living creature were removed, all these sensory qualities would cease to exist. His stance was that our senses were also fabricating tastes, odors, and colors that we experience. These qualities weren't properties of an objective reality; rather, they were properties of our senses constructing our perception of the world.

When we talk about objective reality in this context, we mean something that exists independently of any conscious observer. For instance, the moon existed before there was any life on Earth or even in the universe. Its existence doesn't rely on the perceptions of creatures. Galileo's assertion was that colors, odors, tastes, and similar qualities are not real in the sense of this objective reality. Instead, they exist as experiences, as real experiences. For example, a headache is a real experience even though it wouldn't exist without the person perceiving it. So, Galileo's ideas challenged not only our understanding of the physical world but also the nature of our sensory experiences and how they relate to reality.

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