It seems necessary to explain the fourth dimension of the wilayat in more detail for the benefit of the readers.
The fourth dimension is the universal authority that the Prophet and the Ahlul Bayt have been vested with by the Almighty Allah. It is an authority that makes it possible for the wali to exercise his power over everything that exists. In the words of Ayatullah al-Khumayni, “It is a vicegerency pertaining to the whole of creation, by virtue of which all the atoms in the universe humble themselves before the holder of authority.”
This authority of the chosen servants of Allah is totally dependent on His discretion and power. It should not be seen in the horizonal form but in the vertical form vis-à-vis the power of Almighty Allah. As long as we maintain the vertical hierarchy of the power, we have safeguarded the tawhid (unity and oneness) of Allah.
For example, all Muslims believe that it is Allah who gives life and death to the people. The Quran itself says,
“Allah takes the souls at the time of their death.” (39:42)
But at the same time, the Quran also attributes death to the angels by saying,
“Say: It is the angel of death (who is given charge of you) who shall cause you to die.” (32:11)
If you place the imports of these two verses side-by-side (i.e., horizontal form), then you are guilty of shirk, polytheism; but if you place them in the vertical form (with the power of the angels beneath and dependent upon the power of Allah), then you have safeguarded the tawhid.
Similarly, if we place the power and authority of the Prophets and the Imams in the vertical form (with the conviction that their power is beneath and dependent upon the power of Allah), then we have safeguarded the tawhid as well as the status of the chosen servants of Allah.