Logicus to Likebox: I suggest Likebox should adopt good faith and civility and consider whether it is not Logicus who is silly and ridiculous and misunderstands here, but rather perhaps Likebox who is insufficiently English-literate to understand the problems with this passage. For as it stands the now revised principle is still vulnerable to an elementary counterexample. For it now states: 
 "He thought about the case of a uniformly accelerated box, and noted that it would be indistinguishable from a box sitting still in an unchanging gravitational field." 
 But a uniformly accelerated box is clearly distinguishable from a box at rest - the former is moving but the latter is not. 
 
 Is the principle this sentence is unsuccessfully trying to articulate maybe something like the following principle ?: 
 
 'A person inside a windowless lift who dropped a ball would be unable to tell from the ball's accelerated fall to the floor whether the lift was at rest at some location in a gravitational field or rather in a completely matter-free space not in any gravitational field but moving 'upwards' with the same acceleration as that prevailing at the resting lift's location in the gravitational field.' 

 And is it maybe something like this principle Einstein proclaimed, rather than the mistaken principle that a gravitationally accelerated motion is indistinguishable from a uniformly accelerated motion ?  

 This article is pedagogically appalling !