Symbolism began as a means of concealment, not deceptive, but as the result of a realization through that which was the teaching principle that, perhaps if the fullness of a teaching were to be known explicitly, then there could be confusion caused in the minds of people who attempted to absorb but could not, so some pictographic forms were used to assist comprehension. So, even though it was sincere, it was still a form of corruption of the purity of teaching, and yet a necessary corruption.
We see a symbol as a drawing projected into a physical construct; that physical construct is built according to precise proportions. Having been built to exactness, it is able to accommodate; it is a resonant circuit for the energies of that facet of teaching it represents. One versed in their respective teaching can call forward that which it represents and so that which you term charging or loading occasions. That resonant circuit then is charged, but we qualify this by saying that the energies, which are introduced in charging, will not remain unless that one with the ability to charge, is itself as an entity, absorbed into at least the stage with which that knowledge is concomitant.
We are talking in general terms of symbols at the moment. Those entities that are well beyond the teaching, the stage which that symbol represents, are able to channel through lasting energies into a particular symbol, but that symbol must associate with the energies of that one who does the charging of the symbol or the pictographic form.