The predicament of the people in the late 19th century was that while they found the empirical agenda initiated by Newton convenient where experimental science could be morphed to a celestial scale, they had no understanding of the components which went into that agenda and particularly the 'definitions' which amount to false or flawed perspectives.

"This absolute time can be measured by comparison with no motion; it has therefore neither a practical nor a scientific value; and no one is justified in saying that he knows aught about it. It is an idle metaphysical conception."
Mach, Analyse der Empfindungen, 6th ed.

Although absolute time within the umbrella of the Equation of Time is actually a timekeeping term but has no intrinsic value no more than relative time has nor can these terms can be matched with the natural noon cycle and the 24 hour cycle which the Equation of Time bridges, Mach gets at least one thing right.

There is no external reference for rotation as an isolated motion at a rate of 15° per hour and consequently a full 360° rotation in 24 hours. An experiment would be to measure the length of time it took the Sun to cross the observer's meridian each day using a sand clock, each cycle would generate a different volume of sand corresponding to the individual variations in the daily cycle. By combining all the sand together and dividing them into equal amounts, the corresponding value would be 24 hours, the more days measured and divided equally the closer to a volume consistent with 24 hours. This is what the Equation of Time does and why there is no external reference for rotation at a rate of 4 minutes for each 1° of rotation.