El mundo está repleto de señales que no percibimos. Las criaturas diminutas viven en un mundo diferente de fuerzas poco familiares. Muchos animales “de nuestra escala exceden en mucho el alcance de nuestra percepción de sensaciones familiares. Los murciélagos esquivan los obstáculos haciendo rebotar en ellos ondas sonoras de frecuencia que yo no alcanzo a oír, aunque algunas personas sí pueden hacerlo. Muchos insectos ven el ultravioleta y siguen las invisibles «guías» del néctar de las flores hasta lo que para ellos es una fuente de alimentos y de polen que acarrearán hasta la siguiente flor para su fecundación (las flores crean estas trazas orientadoras de color en su propio beneficio, no en el de los insectos).
¡Qué seres tan poco perceptivos somos! Rodeados de tantas cosas fascinantes y reales que no vemos (oímos, olemos, tocamos, saboreamos) en la naturaleza, y, no obstante, tan crédulos y predispuestos a la aceptación de nuevos poderes que confundimos los trucos de magos mediocres con percepciones de un mundo psíquico más allá del nuestro. Lo paranormal puede ser una fantasía; desde luego es un refugio para muchos charlatanes. Pero los poderes de percepción «parahumana» están a nuestro alrededor en las aves, las abejas y las bacterias.

"Bumblebees detect the polarization of sunlight, invisible to uninstrumented humans; put vipers sense infrared radiation and detect temperature differences of 0.01C at a distance of half a meter; many insects can see ultraviolet light; some African freshwater fish generate a static electric field around themselves and sense intruders by slight perturbations induced in the field; dogs, sharks, and cicadas detect sounds wholly inaudible to humans; ordinary scorpions have micro — seismometers on their legs so they can detect in darkness the footsteps of a small insect a meter away; water scorpions sense their depth by measuring the hydrostatic pressure; a nubile female silkworm moth releases ten billionths of a gram of sex attractant per second, and draws to her every male for miles around; dolphins, whales, and bats use a kind of sonar for precision echo-location.
The direction, range, and amplitude of sounds reflected by to echo-locating bats are systematically mapped onto adjacent areas of the bat brain. How does the bat perceive its echo-world? Carp and catfish have taste buds distributed over most of their bodies, as well as in their mouths; the nerves from all these sensors converge on massive sensory processing lobes in the brain, lobes unknown in other animals. how does a catfish view the world? What does it feel like to be inside its brain? There are reported cases in which a dog wags its tail and greets with joy a man it has never met before; he turns out to be the long-lost identical twin of the dog's "master", recognizable by his odor. What is the smell-world of a dog like? Magnetotactic bacteria contain within them tiny crystals of magnetite - an iron mineral known to early sailing ship navigators as lodenstone. The bacteria literally have internal compasses that align them along the Earth's magnetic field. The great churning dynamo of molten iron in the Earth's core - as far as we know, entirely unknown to uninstrumented humans - is a guiding reality for

How fathomless the mystery of the Unseen is! We cannot plumb its depths with our feeble senses - with eyes which cannot see the infinitely small or the infinitely great, nor anything too close or too distant, such as the beings who live on a star or the creatures which live in a drop of water... with ears that deceive us by converting vibrations of the air into tones that we can hear, for they are sprites which miraculously change movement into sound, a metamorphosis which gives birth to harmonies which turn the silent agitation of nature into song... with our sense of smell, which is poorer than any dog's... with our sense of taste, which is barely capable of detecting the age of a wine!

Ah! If we had other senses which would work other miracles for us, how many more things would we not discover around us!

What senses do we lack that we cannot see or hear another world all around us?

Perceive that which cannot be seen with the eye.

You imagine that what you can't understand is either spiritual or does not exist. The conclusion is quite wrong; rather there are obviously a million things in the universe that we would need a million quite different organs to understand. For example, I perceive by my senses what makes a magnet point north, what makes tides rise and fall, and what becomes of an animal after death. Your people are not proportioned to perceive such miracles, just as someone blind from birth cannot imagine the beauty of a landscape, the colors of a painting or the shadings of an iris. He will imagine them as something palpable, edible, audible or olfactory. Likewise, if I were to explain to you what I perceive by the senses you do not have, you would interpret it as something that could be heard, seen, touched, smelled or tasted; but it is not like that.

What do we know ... of the world and the universe about us? Our means of receiving impressions are absurdly few, and our notions of surrounding objects infinitely narrow. We see things only as we are constructed to see them, and can gain no idea of their absolute nature. With five feeble senses we pretend to comprehend the boundlessly complex cosmos, yet other beings with wider, stronger, or different range of senses might not only see very differently the things we see, but might see and study whole worlds of matter, energy, and life which lie close at hand yet can never be detected with the senses we have.

With five feeble senses we pretend to comprehend the boundlessly complex cosmos, yet other beings with wider, stronger, or different range of senses might not only see very differently the things we see, but might see and study whole worlds of matter, energy, and life which lie close at hand yet can never be detected with the senses we have.

What do we know,” he had said, “of the world and the universe about us? Our means of receiving impressions are absurdly few, and our notions of surrounding objects infinitely narrow. We see things only as we are constructed to see them, and can gain no idea of their absolute nature. With five feeble senses we pretend to comprehend the boundlessly complex cosmos, yet other beings with a wider, stronger, or different range of senses might not only see very differently the things we see, but might see and study whole worlds of matter, energy, and life which lie close at hand yet can never be detected with the senses we have. I have always believed that such strange, inaccessible worlds exist at our very elbows, and now I believe I have found a way to break down the barriers.

We are an animal that has acquired the ability to perceive that it is an animal.

perceiving the world” entails a process of apprehending whatever presents itself to us. This particular “perceiving” is done with our senses and with our will.

We humans like to imagine that we have an objective knowledge of the world. We take it for granted that what we perceive on a daily basis is reality—this reality being more or less the same for everybody. But this is an illusion. No two people see or experience the world in the same way. What we perceive is our personal version of reality, one that is of our own creation. To realize this is a critical step in our understanding of human nature.

Our perceptions are fallible. We sometimes see what isn't there. We are prey to optical illusions. Occasionally we hallucinate. We are error-prone.

Perceptibility is a kind of attentiveness.