One afternoon in the middle of the nineteenth century, August Kekulé, the eminent German chemist, had a daydream in which he saw a snake trying to swallow its own tail.

This is a traditional symbol, known as οὐροβόρος (ouroboros), harking back to alchemy and Gnostic allegory. On this occasion, Kekulé had allegedly been thinking about the structure of the benzene molecule, which had been an intractable problem at the time. He later reported that this vision had guided his thought towards the idea that the molecule had the form of a ring, and was his most enduring claim to fame.

οὐροβόρος is an enduring thread in different sciences. In biology and physiology it can be taken to represent feedback loops which characterise many control processes, such as the regulation of sugar in the blood, the control of blood pressure, and that of balance and orientation in space.

Although much of Gnosticism may now seem occult verging on witchcraft, at its heart was the concept of γνῶσις (gnosis), knowledge in the sense of wisdom and deep understanding, rather than the memorisation of many simple facts. Key to this γνῶσις was self-knowledge, hence the Delphic maxim γνῶθι σεαυτόν (gnothi seauton), the exhortation to know yourself.

In the 150 years since Kekulé’s daydream, we have come to learn a great deal about the way that our bodies work, and in particular how our sensory and neural systems work. Thanks to the latest scanning technology, which is heavily dependent on ingenious computational techniques, we can now observe how different parts of the brain activate and respond to different stimuli, activities, and thought itself.

We have also learned that, whilst we can improve our technology to enhance our abilities, our anatomical and physiological limitations also determine what we can and cannot do.

You can hold a pair of binoculars to your eyes and see a stag in the far distance, but you cannot instantaneously leap over to stand beside the deer.

Equally we can project highly realistic images in small displays in front of each eye, but if we mismatch head movement with shift in those images, we will confuddle those parts of the brain which keep us oriented in space, and cause motion illness, or worse.

The grand experiment in trying to deliver virtual reality (VR) headsets to consumers is gradually reaching its denouement in the form of the Oculus Rift.

Bolstered by the increasing availability of small high-quality displays from the smartphone industry, it looked as if it had all the problems addressed, and that an affordable headset could ship in large quantities.

But there was a nagging problem which remained. A lot of previous experience with VR systems had shown that motion illness could turn what should have been exhilarating and amazing into an overwhelming feeling of near-death.

As the developers in Oculus VR have pushed the bounds of sheer technology, so they have defined the performance required to minimise sensory mismatch, and the risk of motion illness. With the shared experience of games developers and testers, they have now been able to set the minimum standards necessary, which are towards the upper limit of what is reasonably achievable by current consumer computer systems. And that minimum significantly exceeds anything currently available from Apple.

As a result, as I detailed here, they have announced that the first consumer version of the Oculus Rift will require a Windows computer with very high-end graphics, making it attractive only to the dedicated PC gamer for the time being.

Similar problems are arising in other innovative applications of technology, such as wearable battlefield systems for military combat. There are conflicts between what can be achieved by the kit, and what the human inside can cope with.

I always have a heavy heart when I come across these barriers, and dearly wish that instead of running far and fast with new materials, electronics, and hardware wizardry, we could start by understanding the capabilities and limitations of the human: γνῶθι σεαυτόν indeed.

Few other Delphic maxims have served us so well for so long.