The birds nest and the young and the dam. You can take the young or the eggs but not the dam that it may go well with thee.
The symbols here are about the higher influences, the upper sephirot of Chokmah and Binah. The dam or the progenitor is left alone because the source of all good cannot be stopped. Birth must keep taking place. The product of this birth, the eggs and the young are fair game in that their purpose is to be brought into manifestation. You are essentially harvesting them. Taking the mother or dam alone leaves your harvest without nurture. In this case your thoughts without the certainty of their issuing forth. The young and the eggs are your understanding of the products of your thinking. In each case can they be taken because thought builds upon itself and flows according to divine wisdom.
Every house must be builded with a parapet, so as not to bring blood upon the house should a man fall from it.
The house is your own internal unity of thinking. The wall or parapet is Torah or the unity and the man is the initiating force. There must always be a place to begin from in order to promote harmony and unity in thinking. Torah or the protection of Torah as a series of unified expressions of unity provides this fence or starting point for the extension of inspiration and new Torah meanings.
Thou shalt not sow thy vineyard with two kinds of seed; lest the fulness of the seed which thou hast sown be forfeited together with the increase of the vineyard. The seeds are your initial inspirations, the vineyard the place of higher thought from wine and intoxication, the sense of letting go is here. The fulness is the ripening of a seed which overshadows the growth of dual ideas competing for manifestation. Be clear. Be one in your sowing and then be one in your reaping.
Thou shalt not plow with an ox and an ass together. Everything you use to promote your ideas into manifestation must be harmonious in their actions together. An Ox and a donkey would pull in opposite directions therefore defeating your purpose. Again the idea of one and of unity is presented.