ALL of what we call ‘reality’ may actually be subjective, that is beholden to our powers of perception, according to Theosophy.
If, as in the words of the dying Buddha, “all compounds are perishable” then all collections of atoms are to be considered ‘illusions.’
They are, according to The Secret Doctrine (1:329), because they are the “creation of the perceiving Ego.” But this must not be considered a solipsistic argument. If we only knew how to get past our five senses we could contact the underlying ‘reality’ of physical things.
The term “Ego” here must ultimately refer to a personal state, and as such must always relate to specific ‘states’ of consciousness. But this is only from our plane of perception. According to The Secret Doctrine (1:330), once we have gotten past that plane, and scaled the “peak of Omniscience,” the “knowledge of things-in-themselves” is immediately available to us.

The Illusion of Motion
One of the best ways to describe what Theosophy is, arts reporter Ali Snow remarked on a Utah Public Radio show, “is to think of it as a kind of fusion of religion and science.”
“A desire to prove or to explore some of the mystical forces that made religion work and make the spiritual world work.”
A striking example of this kind of fusion is H. P. Blavatsky’s description how “the sense of sound is the first thing that manifests itself in the universe … in correspondence with colors or sight.”

Colors and Sound
About this sensory synesthetic power Blavatsky wrote:
“If you could only see clairvoyantly a person playing a piano, you would see the sound as plainly as you hear it.”
“You can even put cotton in your ears—you will see the sound and every little note and modulation that you could not do otherwise.”
Synesthesia
Making reference to this sensory merging (known today as “synesthesia”) she explained: “One would merge into the other. You can taste sound, if you like, too. There sounds which are exceedingly acid, and there are sounds which are exceedingly sweet, and bitter, and all the scale of taste, in fact.”
“There is no nonsense, I say it seriously, and you will find it so if you want to know about the super-physical senses.”
(Secret Doctrine Dialogues p. 86)
Alexander Scriabin, a Russian pianist and composer who was deeply influenced by Theosophy, visualized a grand magnum opus which he titled “Mysterium.” Click the link here to listen to Nora Eccles, Harrison Museum of Art as the three curators describe the exhibit, Painting Music: Enchanted Modernities, who gives us a personalized tour of the Theosophy promoted power (click below the photo):

Synesthete Elisabeth Sulser
Click to start below:
This interesting phenomenon is demonstrated practically by the multiple senses of a unique synesthete from Zurich, Switzerland named Elizabeth Sulser. A psi investigator writes:
“Her particular combination of senses is so unique that she is the only person in the world documented to have it.”