Formation and removal
Wilders often present the challenge of a block, particularly where channeling carries a cultural stigma or fear. It is a coping mechanism he or she has unconsciously developed to avoid the reality of his or her ability to channel. In addition to protecting the wilder from the mental anguish related to channeling, a block may be a physical protection against the sickness and ultimate death which three in four wilders suffer.
Blocks make it so a channeler can't channel at will unless certain circumstances are met. Those circumstances are different for each person who develops a block. Early on, before the channeler knows he or she is using the One Power, the occurrences may seem like miracles or simply unexplained phenomenon. They may seem to happen when the unwitting channeler wants something desperately or is in a specific emotional state, and only then. Upon learning the true nature of his or her abilities, the block persists--still those circumstances must be met. Realizing the full potential of a blocked channeler is severely hampered.
Blocks can be removed, though not easily. Just as blocks are specific to an individual, so is the method to break the person's block. Sometimes an intense experience can shock a person into channeling where he or she was formerly blocked, or perhaps a person may be tricked into thinking those "necessary" circumstances are met. However broken, once a block has been bypassed it is gone for good and the Source is forever easily accessible.
Nynaeve al'Meara took great pride in her knowledge of herbs and healing remedies quite as village Wisdom. When a patient of hers was sick or injured beyond the capabilities of herbal healing, Nynaeve would become upset, extremely angry at the injury or sickness. An incredible thing would happen after she got angry--the patient would have an inexplicable, miraculous recovery.
Before Moiraine came to Emonds Field, Nynaeve would never have entertained the notion of these miracles being connected in any way to the One Power. When the Aes Sedai explained the phenomenon bearing the clear hallmarks of channeling, Nynaeve denied it vehemently at first; she still thought, "the Power was a filthy thing. She would have nothing to do with it." Slowly, slowly, Nynaeve came around to the concept and embraced her potential. She had been passionate about healing, and this easily transferred to a passion for Healing.
The acceptance of her channeling ability was not enough to enable easy access to the Power. While among the most powerful channelers alive, Nynaeve could not even sense the Source, let alone form weaves, unless filled with anger. Admittedly, she was frequently angry, and could often work up a good anger, but in the calm, open state of mind Aes Sedai enter to embrace the source, Nynaeve was thoroughly blocked. If while holding saidar Nynaeve's anger slipped into fear or another emotion, so did saidar slip away. Many Aes Sedai had suggestions for breaking her block. Theodrin tried to shock Nynaeve with buckets of water, deprived Nynaeve of sleep, and anything else she could think of. Nothing seemed to work, all a waste of time to a frustrated Nynaeve, and saidar remained largely elusive.
It wasn't until a near death experience that Nynaeve broke through her block. While in Ebou Dar, Moghedien struck at Nynaeve's boat with balefire and nearly succeeding in drowning her. Nynaeve's fear and desperation as she sank into the river, on the very edge of consciousness, she surrendered to her impending death. With that true and utter surrender, she broke her block and channeled her way to escape and survival. While she still struggled with her temper, Nynaeve's channeling ability was no longer contingent on anger.
—Theodrin, Lord of Chaos, Chapter 13
You could say that Theodrin Dabei had a weakness for men. More accurately, men gave Theodrin strength where the One Power was concerned. As a wilder, she found she could inexplicably cause a boy to want to kiss her or, conversely dissuade a boy from that desire. Her block was such that Theodrin could channel in the presence of a man for whom she felt an emotion: attraction or loathing. Without a man in the vicinity, or with a man for whom she felt neither emotion, she "might as well have been a tree as far as saidar was concerned."
Theodrin's block was broken by a ruse designed by Sheriam. In contravention of the White Tower's normal policies against fraternization between initiates and male personnel, Theodrin's attraction to Marel, a stableboy with "gorgeous eyes," was encouraged and the young man attended Theodrin's lessons, enabling her to participate. One day, Marel's twin sister Charel dressed in Marel's clothes and replaced him in the classroom. After Theodrin had channeled in the supposed presence of Marel, the object of her desire revealed her true identity. Theodrin was so shocked that she fainted, and from that point on she could channel at will.
When she was taken to the White Tower, Tarna Feir was unable to touch saidar unless she had her eyes closed, and therefore was effectively unable to channel. When one cannot see the flows, learning weaves is next to impossible. Tarna's block was overcome with severe physical pain:
—Tarna Lord of Chaos, Chapter 13
Not particular to female channelers, those who learn to wield saidin may also come up against a block. Fedwin Morr was barred from realizing his full channeling potential. He did not truly believe he could affect that which he could not see, a limitation that was a self-fulfilling prophesy. As an Asha'man, he had a fair amount of strength in the Power, but his weaves began to fade at fifty paces. At one hundred paces, Fedwin could not channel a even thread of saidin.
Whether or not Fedwin overcame his block before his death is unknown.
Androl Genhald's block
Before he came to the Black Tower, leatherworking was one of the many crafts Androl Genhald followed. Androl developed a block that prevented him from channeling the One Power without holding a strap of leather. After joining the Black Tower this block was beaten out of Androl by Mazrim Taim.