יחזקאל, פרק מ״ה, פסוק י״א

Establishing a foundation of economic and moral justice requires a uniform and fair system of weights and measures. Absolute precision in the ratios between different units prevents fraud and injustice, whether in daily trade or in the collection of taxes. At the center of this system is a fixed, unchanging ratio between the largest unit of measurement and the smaller units derived from it.

The primary and largest measure is the Homer, which contains thirty Seah and serves as the standard for both dry and liquid goods [רש״י, מצודת ציון, רד״ק, מלבי״ם]. From the Homer, two smaller measures are derived: the Ephah, used for grains and solid goods, and the Bath, used for liquids like oil and wine. The primary approach among commentators is that these two smaller measures must be absolutely equal in their volume and calculation. Their shared purpose is to accurately measure and hold the required offerings and taxes [רש״י, מצודות, ביאור שטיינזלץ].

Although the liquid and dry measures share the exact same volume, there is a practical difference in how they are collected. The division of liquids is described in a way that implies an actual physical separation, because a full Bath of liquid was literally separated from the Homer. In contrast, the division of dry goods is described in purely mathematical terms. This is because a full Ephah of grain was not physically separated; instead, only a sixth of an Ephah was taken as a tax for the prince [מלבי״ם].

The guiding rule of this entire system is that the smaller measures are entirely subordinate to the Homer. The commentators agree that this creates an absolute relative dependence. If authorities ever decide to increase or decrease the total volume of the Homer, they are obligated to adjust the Ephah and the Bath proportionally, ensuring they always remain exactly one-tenth of the larger measure. This strict legal framework is designed to protect the public from government corruption, ensuring that a ruler cannot arbitrarily enlarge the smaller measuring vessels used for tax collection in order to exploit the people [מלבי״ם].