From the Rebbe’s explanations:
– The 2nd of Nissan marks the yahrzeit of the Rebbe Rashab. It is also the beginning of the leadership (‘nesius’) of his only son, the Rebbe Rayatz. In his very first maamar – ‘Reishis Goyim Amalek’ – he gave a wondrous explanation of the eternal aspect of the tzaddik’s effect on the world.
In the maamar he explains that the spiritual impurity of Amalek has no absolute value or lasting existence. This is in contrast to holiness.
Holiness, since it has an open connection with G‑d, is similar to Him in terms of its absolute and constant existence.
He speaks of the fact that G‑dliness penetrates not only the ‘lights’, but also the ‘vessels’ of the world of Atzilus. Furthermore, anything that G‑d designates as a mitzvah (that is, as a fitting receptacle for holiness) also acquires this quality. Therefore:
‘The physical parchment (used for the words of the Torah), the wool of the tzitzis, and [other objects used for a mitzvah]… exists as an absolute existence.’
He continues by saying that with Tzaddikim, everything they use becomes absolutely holy. Regarding this he told the story of his father, the Rebbe Rashab, who after the passing of the Rebbe Maharash, entered into the room for yechidus, stood next to the table and chair, and, in effect, relived yechidus. This was brought as an example of how even the physical objects in the room had become holy. In fact, not only a table which was used directly for a mitzvah, such as for writing Torah, becomes holy, but even objects used for everyday tasks, done by the tzaddik for the sake of heaven become holy.
The reason for this is that everything holy stems from G‑d, whose Holiness is totally unlimited.
It is not bound to space or time, and remains unchanged under all conditions. For this reason, when connected with the holiness of a tzaddik, even mundane objects become holy — and as explained in the maamar, similar to the absolute holiness of the vessels of the world of Atzilus.
From the Rebbe’s talk on Shabbat Parshas Vayikra, 5747 (1987). Free translation.