Soil systems, the foundation for terrestrial life, have unrivalled complexity. What can be seen of them is mostly mineral and inert, but this visible material contains uncountable numbers of organisms that affect how well soil systems can support plant growth. Soil is likely the most spatially complex of all ecological systems, but at a much smaller scale than can be appreciated with the naked eye; it is a jungle of minerals, biofilms, roots, pore space, and soil fauna at a nanoscale. To grasp and utilize the potentials of soil systems more fully, we need to factor into our thinking and practices these invisible or barely visible components, together with the more observable portion of soil systems.