by ourselves

by (one)self

1. Alone. Because there's usually so much going on with the kids, I really enjoy spending a quiet Saturday night by myself.
2. Through one's own efforts alone. You can't move that table all by yourself! Here, let me help you. My little girl loves to get dressed by herself, so tutus and cowboy boots have become the norm around here.

by ourselves

 
1. with no one else present; alone. Do we have to sit here by ourselves? Can't we sit with Mary and Max? We like to eat by ourselves, so we can talk about private matters. 2. with the help of no one else. We can do it by ourselves. Can we lift this by ourselves, or do we need some help?
See also: ourselves
References in classic literature ?
or find us by ourselves, seeking entertainment in yelling, and sobbing, and rolling on the ground, divided by the whole room?
Tom said we better jump out and tag along after them, because they was going our way and it wouldn't be comfortable to run across the ghost all by ourselves.
If a man's no use, he can go, and we can manage by ourselves.
And we will sing, all by ourselves, till we swoon away with delight.
To an extent that can be true, because there are times that things become really tense and we'd much rather be at home by ourselves not doing anything at all to do with music.
And so our brand economy discloses a task for spiritual maturity: knowing and being known by ourselves and others, without being governed by what we buy.