Our

experience

hitherto

justifies

us

in

trusting

that

nature

is

the

realization

of

the

simplest

that

is

mathematically

conceivable

I

am

convinced

that

purely

mathematical

construction

enables

us

to

find

those

concepts

and

those

lawlike

connections

between

them

that

provide

the

key

to

the

understanding

of

natural

phenomena

Useful

mathematical

concepts

may

well

be

suggested

by

experience

but

in

no

way

can

they

be

derived

from

it

Experience

naturally

remains

the

sole

criterion

of

the

usefulness

of

a

mathematical

construction

for

physics

But

the

actual

creative

principle

lies

in

mathematics

Thus

in

a

certain

sense

I

take

it

to

be

true

that

pure

thought

can

grasp

the

real

as

the

ancients

had

dreamed

Albert

Einstein