Toward Ecosophy

Not really. The CGD has its own distinctive version of occult philosophy, and if you're only on the first knowledge lecture, getting into some other version will likely confuse you. You might consider working with the other three books in that sequence, Coelbren, The Litany of the Tree of Life, and The Mysteries of Merlin (soon to be reprinted in an improved form as Merlin's Wheel). Alternatively, you might have a look at Celtic mythology and legend.