Morphic Fields are like Electromagnetic Fields
Sheldrake’s metaphors suggest that the morphic fields are objective, autonomous realities. As such, they are supposed to be like electromagnetic fields, but of a different nature.
Electromagnetic fields are abstract and invisible, detectable only by their ability to interact with particular arrangements of matter, like ionized gases or magnetically polarized metals. Similarly, morphic fields, which are equally abstract and invisible, are detectable only by their ability to resonate with particular arrangements of matter under particular circumstances, like those of embryonic development or electrochemical activity in the brain.
Sheldrake thus places his views on a firmly realist ground: Morphic fields exist objectively in nature as part of it, next to other objective parts of nature like atoms and fields of other types. In other works, Sheldrake also suggests that mind itself is a kind of field centered in the brain but extending beyond the brain, much like the electromagnetic field of a magnet is centered in the magnet but extends beyond it. Here again, Sheldrake’s metaphors seem to be underpinned by a realist assumption: Minds are objective and causally-effective fields just like electromagnetic fields. As such, mind-fields are a part of nature, but not the very medium of all reality, as idealism entails.