Whereas chesed and gevura signify unbounded loving-kindness and its constriction so that finite creatures can receive according to their ability, netzach and hod are the two sefirot which define the ability of the recipient to receive. In addition, they perform together as the "joint distribution committee", which decide how, and in what measure, each recipient will get its due.
Let us give an analogy: A professor wants to teach his student calculus, let us say. Of course, the professor wants to teach his students as much as possible in the shortest possible time, so that the students can go on to other subjects in math (this is the attribute of chesed, the desire to give more and more is the attribute of chesed). But the professor is well aware that his students' present level of understanding is insufficient to grasp the entire theory of calculus in a single lesson. So he divides up the subject into several lectures, explaining only one section of the theory at a time (this is the attribute of gevura, limiting and dividing the outflow of benevolence). When the professor actually explains the subject, he takes into account the individual abilities and limitations of each of his students, and he explains the subject accordingly (this signifies the functioning of the attributes of netzach and hod).
The powers of prophecy…derive from the sefirot of netzach and hod
On the Fourth day, the sun and the moon and the stars were created. Light was too infinite and sublime to be of use to the finite worlds; thus, on the Fourth day, a finite, usable form of light was apportioned. On the Fifth day birds and sea-creatures were created, the first recipients of G-d's benevolence and the first created beings able to fulfill the commandment pru u'rvu, "be fruitful and multiply".
According to Kabbala, the powers of prophecy and divine inspiration derive from the sefirot of netzach and hod -- for they actually receive the effusion of G-dly light.
Just as the sefira of tiferet harmonizes and balances chesed and gevura, so too, yesod harmonized and balances netzach and hod. However, there is an additional unique aspect of yesod in that it acts as the channel through which malchut receives its proper measure of light and life force. Whereas netzach and hod distribute the divine efflux and determine the character and the amount the recipients receive, yesod is the actual distribution point. Thus, yesod functions as the connector between all of the sefirot which precede it, and the recipient, malchut, below it.
In order for the distribution to reach its intended destination, there must be a proper channel of communication between the giver, yesod, and the receiver, malchut. The distributor (yesod), must be able to identify the recipient (malchut) in order to apportion content to its intended recipient. This is why yesod is also called emet ("truth") in Kabbala. Yesod makes sure that the light and life force is delivered to the proper destination.
But the "identification" process does not only mean that the recipient fulfills the necessary conditions that must be met in order for it to be able to receive. Much more than this, there must be an internal bond between yesod and malchut, a bond of love and understanding. Yesod arouses the desire to receive from within malchut, and malchut in turn arouses within yesod the desire to give. In this way, yesod unites itself with malchut in complete empathy, so that the "giving" is direct, face to face, and indirect, back to back, as it were.
Thus, yesod can be defined as the divine attribute which binds G-d to His creation in a bond of empathy and love. This is why the sefira of Yesod is also called "saint" ("tzadik" in Hebrew) as in the verse "a saint is the foundation of the world" (Proverbs 10:25). A tzadik, or saint, arouses mankind to seek G-d. At the same time he draws down G-d's compassion and goodness into the world. Thus he is the foundation of the world.
Transcend your limited nature… that part of yourself which is simply natural
On the sixth day of Creation, the animal kingdom was created, including the first man and woman, Adam and Eve, created in the Divine Image. Both animals and man are told "be fruitful and multiply", which also means to use G-d's benevolent kindness to grow and expand in G-d-consciousness. But an additional duty is given to man. Be fruitful and multiply and rule over the animals and the birds and the fish. In other words, be over and above them -- and not among them. Transcend your limited nature, transcend that part of yourself which is simply natural, like the animal world, and become the Divine Image in which you were created. The drive to do this is initiated by the power of yesod, the tzadik.
Click here to find out what the Kabbalah for Beginners Tutorial is all about.