 Pace Berkeley, the difference between these types of states is not merely a matter of degree: feeling the warmth of a fire is not like a feeling of pain. Feeling the fire is hotter than it was before is a matter of perception, discrimination, or finding out a difference. People can be better at it than others: doctors acquire the skill of feeling pulses that an untrained person cannot and race drivers feel a car going into a skid well before an ordinary motorist can. Feeling pain, giddy, nauseous, or high, by contrast are not a matter of perception, an acquired skill or that which training can fine-tune. Mistakes due to carelessness are ruled out when we talk of sensations qua pain or elation; they are not ruled out when it comes to perception as discrimination or detection.