Magic is rarely spoken about in plain terms, it always seems to be veiled in analogy, hidden behind layers of metaphor, and cloaked in riddles. Some claim that this is the case because true practitioners of magic don't want novices wielding power they don't truly understand, others claim that those who have power simply don't want to share that power, the. There are those who claim that lesser minds simply couldn't handle the true nature of magic, and it's only through understanding riddles like zen koans that the mind becomes disciplined enough to truly comprehend the complexities underlying reality.
One or more of these reasons may be true. Different reasons might be true for different people, perhaps it is simply a tradition that has built up over the centuries... a tradition that has become notoriously hard to break, like industries where "paying one's dues" are considered a part of the process of integrating into the culture. While mortal practitioners of magic debate the need for riddles and metaphor, and mundane citizens of the world don't understand them at all, for familiars, the reasons for analogy and metaphor are clear.
As conduits of the supernatural power, familiars understand the truth about magic. The problem here is that familiars don't understand the ways of the mundane world, they do not have the common point of reference to impart their mystic knowledge to those of the mundane world so they need to meet mortals half way. Familiars grasp fragments of the mundane world, looking through at it in a reverse manner to that of the practitioners of magic who look through the same holes to perceive the unbridled possibility of the supernatural. The fragments of mundane life that match concepts understood by familiars are used as examples for the mages they speak to. Different familiars will see different mortal concepts that ring true for them, and for this reason there may be a hundred different analogies for the same metaphysical concepts. Different practitioners of magic will then choose the analogies that make the most sense to them as a means to bridge the gap between the natural and the supernatural, often using two or more analogies to piece together a meaningful truth.