In Quantum Physics we learn the interconnectedness of everything. One can not throw a pebble into the ocean without making the ocean infinitesimally deeper.
In the Northern tradition the Norns are busy weaving time, past, present and future by the well of Urd.(Here the portrayal of "weaving is that everything is connected or woven together.) In many Native American shamanic cultures the idea that everything is connected is usually represented by the symbol of the spider web. Look at the Internet, "The World Wide Web?"
The Norse Shaman is the spider who weaves the web (of life) in a lucid dream out of the fine threads that come from within. The web not only represents the dreaming of life, but also it's interconnectedness.
Every part of life is connected to every other part, and what affects one affects all to varying degrees. A single thought of love or hate affects the whole Universe, but your body will probably be more affected than the star Betelgeuse, just as a leaf will affect the part of the web it touches more than the rest, though the whole web may quiver.
Although the web is a common traditional metaphor used to explain an actual metaphysical connection between everything, some people find it easier to think of the connection in terms of electromagnetic metaphor of fields within fields in infinite array.
By assuming such an interconnectedness, we can assume the possibility of influence at a distance, which the shamans and witches do and which they use for many types of healing and manifesting.
Brightest of Blessings,