Be on guard

[braggin]

I think it has several different meanings on different levels. First, it's that the heart is the engine of life - it is literally the organ which keeps you alive and breathing. One it fails, you are a goner. And on another level the heart is considered the seat of loving a person and it could mean that loving another person is the essence of what it means to live.

[gaby_ro_2004]

Don't trust every one.

[natashaspy]

I believe it means be careful what you put your faith in, like false idols and such.