  It should be noticed that Place was using the word ‘logical’ in the way that it was used at Oxford at the time, not in the way that it is normally used now. One objection was that ‘sensation’ does not mean the same as ‘brain process’. Place's reply was to point out that ‘this table’ does not mean the same as ‘this old packing case’ and ‘lightning’ does not mean the same as ‘motion of electric charges’. We find out whether this is a table in a different way from the way in which we find out that it is an old packing case. We find out whether a thing is lightning by looking and that it is a motion of electric charges by theory and experiment. This does not prevent the table being identical to the old packing case and the perceived lightning being nothing other than an electric discharge. Feigl and Smart put the matter more in terms of the distinction between meaning and reference. ‘Sensation’ and ‘brain process’ may differ in meaning and yet have the same reference. ‘Very bright planet seen in the morning’ and ‘very bright planet seen in the evening’ both refer to the same entity Venus. (Of course these expressions could be construed as referring to different things, different sequences of temporal stages of Venus, but not necessarily or most naturally so.) 