Performance of what is prescribed; adherence in practice; observance.
Esimerkit
But Miss Thorn relieved the situation by laughing aloud,[...]. We began to tell her about Mohair and the cotillon, and of our point of observation from the Florentine galleried porch, and she insisted she would join us there.
The physics of elementary particles in the 20th century was distinguished by the observation of particles whose existence had been predicted by theorists sometimes decades earlier.
That's a foolish observation.
To observations which ourselves we make / We grow more partial for the observer's sake.
We are to procure dispensation or leave to omit the observation of it in such circumstances.