The spirit has no voice, because where there is a voice there is a body, and where there is a body space is occupied, and this prevents the eye from … - Leonardo da Vinci

If you take as your pattern the wings of feathered birds, these are more powerful in structure of bone and sinew because they are penetrable, that is to say the feathers are separated from one another and the air passes through them. But the bat is aided by its membrane, which binds the whole together and is not penetrated by the air.

Quelli che s’innamorano della pratica senza la scienza, sono come i nocchieri che entrano in naviglio senza timone o bussola, che mai hanno certezza dove si vadano. Sempre la pratica dev’essere edificata sopra la buona teorica, della quale la prospettiva è guida e porta, e senza questa nulla si fa bene.

But leaves of yellowish green do not, when they reflect the atmosphere, create a reflection which verges on blue; for every object when seen in a mirror takes part in the color of this mirror; therefore the blue of the atmosphere reflected in the yellow of the leaf appears green, because blue and yellow mixed together form the most brilliant green, and therefore luster on light leaves which are yellowish in color will be a greenish yellow.