This first of 3 missable achievements is found in Chapter 2. This begins at 06:20
in the video below.
There will be 5 flames you must light by looking at them to open the door with the flame above it. From the start, head forward and look at the eye to the right, backing away to raise its platform. Head up the stairs and make sure flame #1 in the stand at the top is lit when you leave (it turns on/off each time you look away and look back at it).
Through the next door you'll see flames #2 and #3 beside the door as you enter, as well as the flame door to the left that will open for an achievement once they're all lit. Make sure both flames are lit before you head downstairs (or leave them for when you come back to the door).
Head toward the door and look to the left just before you enter it for flame #4. Back away from the next door looking at its eye to open it, then look at your feet as you go toward it and through. Around the next corner to your left is flame #5. Make sure it's lit, then head back to the flame door, ensuring that flame #4 is lit as you pass. When you return, you may turn off flame #2 and/or #3 so make sure they're lit and enter the now-open fire door.
The bridge raises and lowers with you when you jump if you're looking at the eye. Look away and jump, looking back at the eye as you fall to lower it to your level. Get onto the bridge and do the opposite, jumping while looking at it and looking away as you fall. Once you raise it up and get to the sign, you'll get the Spirit achievement.