Because it could make me feel anything from anger to joy, and all the emotions in between.
Anger: when she's a year, or two, or three, or probably older than that and she's fighting with her sisters and they are all screaming at each other and you have to shout to be heard over the melee. And all three of them are tear-stained and you could murder each of them.
Desperation: when she's six weeks old, and she screams, and she screams, and she screams, and you feed her, and she screams, and you hold her and she screams, and her father walks out of the house because he can't take it any more. He comes back, of course he does, he only went round the block, but the tears take longer to stop.
Joy, well maybe not joy, but certainly gratification. When she's three and she's done something naughty, and she knows it. And she isn't allowed a story, and she cries. And you are glad.
Frustration: when she is two and a bit, and she wakes in the night, and she wants you. And you know she's ok, and she knows she's ok, and all she really is is bored. And then she starts crying again. For the fourth time. And you have to get out of bed again. For the fourth time. And you could shake her. If only you didn't have to get out of bed to do it.
Pity: when she's eight weeks old, and has her first injections, and pain enters her world. Or when she's eighteen months and her Bunny is in the washing machine. Or when she's three and she bites her tongue. Or all those times that she hurts and you can't stop it, however much you kiss it better.
Amusement: when she's two, and she has a tantrum. Out of nowhere, arms flailing, face contorted, snot dripping. And you know you should be doing something about it, but all you can do is laugh. And find the camera.
Like she's six weeks old again: when she's twenty six and her heart has been broken. And you find her, at the top of the stairs, in a crumpled heap, sobbing, not as though her heart would break, because it's too late for that. And you gather her into your arms and you rock her backwards and forwards and you murmur into her hair "my baby, my baby".
Because you are forty six, and she is twenty six; or you are thirty three and she is three; or you are both older or younger and anywhere in between; but she is your baby, and she hurts. And her tears are your tears.