Why was Sarah not allowed to give birth until she was 90? It has to do with the balance of good and evil in the world. In the course of the explanation, we will find out about the meaning of the A-T,B-SH. We will not reach a complete explanation yet, but will find out something very important instead.
To arrive at a hidden meaning of words, the Kabbalah sometimes uses the reflection where the first letter of the alphabet becomes the last, the second letter become the one before the last, and so on. Therefore, א becomes ת, and ב becomes ש, and so on. This method is called את-בש.
The first three letters of the alphabet, aleph (א), bet (ב), gimel (ג) have the combined gematria of 6, vav (ו). This hints at the six directions (winds) of the world (space), which were kneaded together with the heaven and earth. After that, the earth (physical matter) was formed, which corresponds to the letter dalet (ד), and dalet includes the four principal elements - fire, wind, water, dust (ארמע).
Then comes the letter hey (ה), which is found in the word "He created them" (בהבראם), which can also be understood as "With hey He created them" - this is the second letter hey in the name of God, the "small hey."
These are the five letters of holiness, standing at the beginning of creation. Then come the four letters of the evil forces (תשרק), hinted at by "empty and void". Thus, with the letter aleph came the letter tav (ת), the evil deceiving husk. This is the rule: when holiness ends, evil, or concealment, begins.
Then came the three letters representing falsehood, sheker (שקר), the next letters at the end of the alphabet. In the letter kuf (ק), there is a long hanging vav (ו), which represents the snake, who spoke falsehood and walks on his belly. It also hints at Haman, who is a snake, and who prepared for Mordechai a gallows of 50 amot high.
Since the evil has no power to act on its own, at the beginning of "falsehood" (שקר) stands the letter shin (ש), which is also a letter of holiness.
Art: Paul Gauguin - Fire By The Water