To do so, we created a journey through the three neural networks of our time that, we believe, represent the wake of his research: 1. The biological neural network, which refers to Neuronal Theory and the Law of Dynamic Polarisation. 2. The artificial neural network, which alludes to the McCulloch-Pitts Mathematical Model of the Neuron, inspired by Cajal’s research and the basis of artificial neural networks and deep learning in AI. 3. The cosmic neural network, representing the work of astrophysicist Franco Vazza and neurosurgeon Alberto Feletti. They have just revealed that the structure of neuronal cells and that of the universe have great similarities in terms of complexity and organisation, as well as internal communication. None of these three networks would have been possible without the visionary mind of the Nobel laureate.